diff --git a/pkg/custom_element/lib/custom_element.dart b/pkg/custom_element/lib/custom_element.dart
index 43366bce36e..5057eb14931 100644
--- a/pkg/custom_element/lib/custom_element.dart
+++ b/pkg/custom_element/lib/custom_element.dart
@@ -249,6 +249,8 @@ class CustomElement implements Element {
     host.createFragment(html,
         validator: validator, treeSanitizer: treeSanitizer);
 
+  InputMethodContext get inputMethodContext => host.inputMethodContext;
+
   bool get isContentEditable => host.isContentEditable;
 
   String get lang => host.lang;
diff --git a/sdk/lib/html/dart2js/html_dart2js.dart b/sdk/lib/html/dart2js/html_dart2js.dart
index eee59ac84ce..37f50412935 100644
--- a/sdk/lib/html/dart2js/html_dart2js.dart
+++ b/sdk/lib/html/dart2js/html_dart2js.dart
@@ -111,7 +111,7 @@ abstract class _EntryArray implements List<Entry> native "EntryArray" {}
 
 @DocsEditable()
 @DomName('AbstractWorker')
-abstract class AbstractWorker extends Interceptor implements EventTarget native "AbstractWorker" {
+class AbstractWorker extends Interceptor implements EventTarget native "AbstractWorker" {
   // To suppress missing implicit constructor warnings.
   factory AbstractWorker._() { throw new UnsupportedError("Not supported"); }
 
@@ -266,12 +266,6 @@ class AnchorElement extends HtmlElement implements UrlUtils native "HTMLAnchorEl
   @DocsEditable()
   String href;
 
-  @DomName('HTMLAnchorElement.origin')
-  @DocsEditable()
-  // WebKit only
-  @Experimental() // non-standard
-  final String origin;
-
   @DomName('HTMLAnchorElement.password')
   @DocsEditable()
   @Experimental() // untriaged
@@ -7849,19 +7843,16 @@ class DocumentFragment extends Node implements ParentNode native "DocumentFragme
         validator: validator, treeSanitizer: treeSanitizer);
   }
 
-  HtmlCollection get _children => throw new UnimplementedError(
-      'Use _docChildren instead');
-
   // Native field is used only by Dart code so does not lead to instantiation
   // of native classes
   @Creates('Null')
-  List<Element> _docChildren;
+  List<Element> _children;
 
   List<Element> get children {
-    if (_docChildren == null) {
-      _docChildren = new FilteredElementList(this);
+    if (_children == null) {
+      _children = new FilteredElementList(this);
     }
-    return _docChildren;
+    return _children;
   }
 
   void set children(List<Element> value) {
@@ -10910,6 +10901,19 @@ abstract class Element extends Node implements GlobalEventHandlers, ParentNode,
   @DocsEditable()
   bool hidden;
 
+  /**
+   * The current state of IME composition.
+   *
+   * ## Other resources
+   *
+   * * [Input method editor specification]
+   * (http://www.w3.org/TR/ime-api/) from W3C.
+   */
+  @DomName('Element.inputMethodContext')
+  @DocsEditable()
+  @Experimental() // untriaged
+  final InputMethodContext inputMethodContext;
+
   @DomName('Element.isContentEditable')
   @DocsEditable()
   final bool isContentEditable;
@@ -14508,6 +14512,10 @@ class HtmlDocument extends Document native "HTMLDocument" {
 class HtmlFormControlsCollection extends HtmlCollection native "HTMLFormControlsCollection" {
   // To suppress missing implicit constructor warnings.
   factory HtmlFormControlsCollection._() { throw new UnsupportedError("Not supported"); }
+
+  @DomName('HTMLFormControlsCollection.__getter__')
+  @DocsEditable()
+  Node __getter__(int index) native;
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -14604,6 +14612,17 @@ class HttpRequest extends HttpRequestEventTarget native "XMLHttpRequest" {
    *
    * This is similar to [request] but specialized for HTTP GET requests which
    * return text content.
+   * 
+   * To add query parameters, append them to the [url] following a `?`,
+   * joining each key to its value with `=` and separating key-value pairs with
+   * `&`.
+   * 
+   *     var name = Uri.encodeQueryComponent('John');
+   *     var id = Uri.encodeQueryComponent('42');
+   *     HttpRequest.getString('users.json?name=$name&id=$id')
+   *       .then((HttpRequest resp) {
+   *         // Do something with the response.
+   *     });
    *
    * See also:
    *
@@ -14622,6 +14641,20 @@ class HttpRequest extends HttpRequestEventTarget native "XMLHttpRequest" {
    * to sending a FormData object with broader browser support but limited to
    * String values.
    *
+   * If [data] is supplied, the key/value pairs are URI encoded with
+   * [Uri.encodeQueryComponent] and converted into an HTTP query string.
+   * 
+   * Unless otherwise specified, this method appends the following header:
+   *
+   *     Content-Type: application/x-www-form-urlencoded; charset=UTF-8
+   * 
+   * Here's an example of using this method:
+   * 
+   *     var data = { 'firstName' : 'John', 'lastName' : 'Doe' };
+   *     HttpRequest.postFormData('/send', data).then((HttpRequest resp) {
+   *       // Do something with the response.
+   *     });
+   *
    * See also:
    *
    * * [request]
@@ -14673,6 +14706,25 @@ class HttpRequest extends HttpRequestEventTarget native "XMLHttpRequest" {
    * * The `Access-Control-Allow-Credentials` header of `url` must be set to true.
    * * If `Access-Control-Expose-Headers` has not been set to true, only a subset of all the response headers will be returned when calling [getAllRequestHeaders].
    *
+   * 
+   * The following is equivalent to the [getString] sample above:
+   *
+   *     var name = Uri.encodeQueryComponent('John');
+   *     var id = Uri.encodeQueryComponent('42');
+   *     HttpRequest.request('users.json?name=$name&id=$id')
+   *       .then((HttpRequest resp) {
+   *         // Do something with the response.
+   *     });
+   *
+   * Here's an example of submitting an entire form with [FormData].
+   *
+   *     var myForm = querySelector('form#myForm');
+   *     var data = new FormData(myForm);
+   *     HttpRequest.request('/submit', method: 'POST', sendData: data)
+   *       .then((HttpRequest resp) {
+   *         // Do something with the response.
+   *     });
+   *
    * Note that requests for file:// URIs are only supported by Chrome extensions
    * with appropriate permissions in their manifest. Requests to file:// URIs
    * will also never fail- the Future will always complete successfully, even
@@ -29175,15 +29227,6 @@ class _BeforeUnloadEventStreamProvider implements
   String getEventType(EventTarget target) {
     return _eventType;
   }
-
-  ElementStream<BeforeUnloadEvent> forElement(Element e, {bool useCapture: false}) {
-    return new _ElementEventStreamImpl(e, _eventType, useCapture);
-  }
-
-  ElementStream<BeforeUnloadEvent> _forElementList(ElementList e,
-      {bool useCapture: false}) {
-    return new _ElementListEventStreamImpl(e, _eventType, useCapture);
-  }
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -29213,6 +29256,11 @@ abstract class WindowEventHandlers extends EventTarget {
   // To suppress missing implicit constructor warnings.
   factory WindowEventHandlers._() { throw new UnsupportedError("Not supported"); }
 
+  @DomName('WindowEventHandlers.beforeunloadEvent')
+  @DocsEditable()
+  @Experimental() // untriaged
+  static const EventStreamProvider<Event> beforeUnloadEvent = const EventStreamProvider<Event>('beforeunload');
+
   @DomName('WindowEventHandlers.hashchangeEvent')
   @DocsEditable()
   @Experimental() // untriaged
@@ -29253,6 +29301,11 @@ abstract class WindowEventHandlers extends EventTarget {
   @Experimental() // untriaged
   static const EventStreamProvider<Event> unloadEvent = const EventStreamProvider<Event>('unload');
 
+  @DomName('WindowEventHandlers.onbeforeunload')
+  @DocsEditable()
+  @Experimental() // untriaged
+  Stream<Event> get onBeforeUnload => beforeUnloadEvent.forTarget(this);
+
   @DomName('WindowEventHandlers.onhashchange')
   @DocsEditable()
   @Experimental() // untriaged
@@ -31580,7 +31633,7 @@ abstract class CanvasImageSource {}
  * * [DOM Window](https://developer.mozilla.org/en-US/docs/DOM/window) from MDN.
  * * [Window](http://www.w3.org/TR/Window/) from the W3C.
  */
-abstract class WindowBase {
+abstract class WindowBase implements EventTarget {
   // Fields.
 
   /**
@@ -32653,9 +32706,6 @@ class _CustomEventStreamProvider<T extends Event>
   String getEventType(EventTarget target) {
     return _eventTypeGetter(target);
   }
-
-  String get _eventType =>
-      throw new UnsupportedError('Access type through getEventType method.');
 }
 // DO NOT EDIT- this file is generated from running tool/generator.sh.
 
@@ -34890,10 +34940,6 @@ abstract class ReadyState {
  */
 class _WrappedEvent implements Event {
   final Event wrapped;
-
-  /** The CSS selector involved with event delegation. */
-  String _selector;
-
   _WrappedEvent(this.wrapped);
 
   bool get bubbles => wrapped.bubbles;
@@ -34931,43 +34977,6 @@ class _WrappedEvent implements Event {
   void stopPropagation() {
     wrapped.stopPropagation();
   }
-
-  /**
-   * A pointer to the element whose CSS selector matched within which an event
-   * was fired. If this Event was not associated with any Event delegation,
-   * accessing this value will throw an [UnsupportedError].
-   */
-  Element get matchingTarget {
-    if (_selector == null) {
-      throw new UnsupportedError('Cannot call matchingTarget if this Event did'
-          ' not arise as a result of event delegation.');
-    }
-    var currentTarget = this.currentTarget;
-    var target = this.target;
-    var matchedTarget;
-    do {
-      if (target.matches(_selector)) return target;
-      target = target.parent;
-    } while (target != null && target != currentTarget.parent);
-    throw new StateError('No selector matched for populating matchedTarget.');
-  }
-
-  /**
-   * This event's path, taking into account shadow DOM.
-   *
-   * ## Other resources
-   *
-   * * [Shadow DOM extensions to Event]
-   * (http://w3c.github.io/webcomponents/spec/shadow/#extensions-to-event) from
-   * W3C.
-   */
-  // https://dvcs.w3.org/hg/webcomponents/raw-file/tip/spec/shadow/index.html#extensions-to-event
-  @Experimental()
-  List<Node> get path => wrapped.path;
-
-  dynamic get _get_currentTarget => wrapped._get_currentTarget;
-
-  dynamic get _get_target => wrapped._get_target;
 }
 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -35621,17 +35630,6 @@ class KeyEvent extends _WrappedEvent implements KeyboardEvent {
     throw new UnsupportedError(
         "Cannot initialize a KeyboardEvent from a KeyEvent.");
   }
-  int get _layerX => throw new UnsupportedError('Not applicable to KeyEvent');
-  int get _layerY => throw new UnsupportedError('Not applicable to KeyEvent');
-  int get _pageX => throw new UnsupportedError('Not applicable to KeyEvent');
-  int get _pageY => throw new UnsupportedError('Not applicable to KeyEvent');
-  @Experimental() // untriaged
-  bool getModifierState(String keyArgument) => throw new UnimplementedError();
-  @Experimental() // untriaged
-  int get location => throw new UnimplementedError();
-  @Experimental() // untriaged
-  bool get repeat => throw new UnimplementedError();
-  dynamic get _get_view => throw new UnimplementedError();
 }
 // Copyright (c) 2011, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
diff --git a/sdk/lib/html/dartium/html_dartium.dart b/sdk/lib/html/dartium/html_dartium.dart
index ab9ff52b06b..9f5f8aba424 100644
--- a/sdk/lib/html/dartium/html_dartium.dart
+++ b/sdk/lib/html/dartium/html_dartium.dart
@@ -101,7 +101,7 @@ HtmlDocument get document {
 
 @DocsEditable()
 @DomName('AbstractWorker')
-abstract class AbstractWorker extends NativeFieldWrapperClass2 implements EventTarget {
+class AbstractWorker extends NativeFieldWrapperClass2 implements EventTarget {
   // To suppress missing implicit constructor warnings.
   factory AbstractWorker._() { throw new UnsupportedError("Not supported"); }
 
@@ -304,12 +304,6 @@ class AnchorElement extends HtmlElement implements UrlUtils {
   @DocsEditable()
   void set href(String value) native "HTMLAnchorElement_href_Setter";
 
-  @DomName('HTMLAnchorElement.origin')
-  @DocsEditable()
-  // WebKit only
-  @Experimental() // non-standard
-  String get origin native "HTMLAnchorElement_origin_Getter";
-
   @DomName('HTMLAnchorElement.password')
   @DocsEditable()
   @Experimental() // untriaged
@@ -8297,16 +8291,13 @@ class DocumentFragment extends Node implements ParentNode {
         validator: validator, treeSanitizer: treeSanitizer);
   }
 
-  HtmlCollection get _children => throw new UnimplementedError(
-      'Use _docChildren instead');
-
-  List<Element> _docChildren;
+  List<Element> _children;
 
   List<Element> get children {
-    if (_docChildren == null) {
-      _docChildren = new FilteredElementList(this);
+    if (_children == null) {
+      _children = new FilteredElementList(this);
     }
-    return _docChildren;
+    return _children;
   }
 
   void set children(List<Element> value) {
@@ -11195,6 +11186,8 @@ abstract class Element extends Node implements GlobalEventHandlers, ParentNode,
 
   bool hidden;
 
+  InputMethodContext get inputMethodContext;
+
   bool get isContentEditable;
 
   String lang;
@@ -15603,6 +15596,10 @@ class HtmlFormControlsCollection extends HtmlCollection {
   // To suppress missing implicit constructor warnings.
   factory HtmlFormControlsCollection._() { throw new UnsupportedError("Not supported"); }
 
+  @DomName('HTMLFormControlsCollection.__getter__')
+  @DocsEditable()
+  Node __getter__(int index) native "HTMLFormControlsCollection___getter___Callback";
+
   @DomName('HTMLFormControlsCollection.namedItem')
   @DocsEditable()
   Node namedItem(String name) native "HTMLFormControlsCollection_namedItem_Callback";
@@ -31609,15 +31606,6 @@ class _BeforeUnloadEventStreamProvider implements
   String getEventType(EventTarget target) {
     return _eventType;
   }
-
-  ElementStream<BeforeUnloadEvent> forElement(Element e, {bool useCapture: false}) {
-    return new _ElementEventStreamImpl(e, _eventType, useCapture);
-  }
-
-  ElementStream<BeforeUnloadEvent> _forElementList(ElementList e,
-      {bool useCapture: false}) {
-    return new _ElementListEventStreamImpl(e, _eventType, useCapture);
-  }
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -31656,6 +31644,11 @@ abstract class WindowEventHandlers extends EventTarget {
   // To suppress missing implicit constructor warnings.
   factory WindowEventHandlers._() { throw new UnsupportedError("Not supported"); }
 
+  @DomName('WindowEventHandlers.beforeunloadEvent')
+  @DocsEditable()
+  @Experimental() // untriaged
+  static const EventStreamProvider<Event> beforeUnloadEvent = const EventStreamProvider<Event>('beforeunload');
+
   @DomName('WindowEventHandlers.hashchangeEvent')
   @DocsEditable()
   @Experimental() // untriaged
@@ -31696,6 +31689,11 @@ abstract class WindowEventHandlers extends EventTarget {
   @Experimental() // untriaged
   static const EventStreamProvider<Event> unloadEvent = const EventStreamProvider<Event>('unload');
 
+  @DomName('WindowEventHandlers.onbeforeunload')
+  @DocsEditable()
+  @Experimental() // untriaged
+  Stream<Event> get onBeforeUnload => beforeUnloadEvent.forTarget(this);
+
   @DomName('WindowEventHandlers.onhashchange')
   @DocsEditable()
   @Experimental() // untriaged
@@ -33925,10 +33923,6 @@ abstract class _XMLHttpRequestProgressEvent extends ProgressEvent {
  */
 class _WrappedEvent implements Event {
   final Event wrapped;
-
-  /** The CSS selector involved with event delegation. */
-  String _selector;
-
   _WrappedEvent(this.wrapped);
 
   bool get bubbles => wrapped.bubbles;
@@ -33966,43 +33960,6 @@ class _WrappedEvent implements Event {
   void stopPropagation() {
     wrapped.stopPropagation();
   }
-
-  /**
-   * A pointer to the element whose CSS selector matched within which an event
-   * was fired. If this Event was not associated with any Event delegation,
-   * accessing this value will throw an [UnsupportedError].
-   */
-  Element get matchingTarget {
-    if (_selector == null) {
-      throw new UnsupportedError('Cannot call matchingTarget if this Event did'
-          ' not arise as a result of event delegation.');
-    }
-    var currentTarget = this.currentTarget;
-    var target = this.target;
-    var matchedTarget;
-    do {
-      if (target.matches(_selector)) return target;
-      target = target.parent;
-    } while (target != null && target != currentTarget.parent);
-    throw new StateError('No selector matched for populating matchedTarget.');
-  }
-
-  /**
-   * This event's path, taking into account shadow DOM.
-   *
-   * ## Other resources
-   *
-   * * [Shadow DOM extensions to Event]
-   * (http://w3c.github.io/webcomponents/spec/shadow/#extensions-to-event) from
-   * W3C.
-   */
-  // https://dvcs.w3.org/hg/webcomponents/raw-file/tip/spec/shadow/index.html#extensions-to-event
-  @Experimental()
-  List<Node> get path => wrapped.path;
-
-  dynamic get _get_currentTarget => wrapped._get_currentTarget;
-
-  dynamic get _get_target => wrapped._get_target;
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -34336,7 +34293,7 @@ abstract class CanvasImageSource {}
  * * [DOM Window](https://developer.mozilla.org/en-US/docs/DOM/window) from MDN.
  * * [Window](http://www.w3.org/TR/Window/) from the W3C.
  */
-abstract class WindowBase {
+abstract class WindowBase implements EventTarget {
   // Fields.
 
   /**
@@ -35409,9 +35366,6 @@ class _CustomEventStreamProvider<T extends Event>
   String getEventType(EventTarget target) {
     return _eventTypeGetter(target);
   }
-
-  String get _eventType =>
-      throw new UnsupportedError('Access type through getEventType method.');
 }
 // DO NOT EDIT- this file is generated from running tool/generator.sh.
 
@@ -38137,17 +38091,6 @@ class KeyEvent extends _WrappedEvent implements KeyboardEvent {
     throw new UnsupportedError(
         "Cannot initialize a KeyboardEvent from a KeyEvent.");
   }
-  int get _layerX => throw new UnsupportedError('Not applicable to KeyEvent');
-  int get _layerY => throw new UnsupportedError('Not applicable to KeyEvent');
-  int get _pageX => throw new UnsupportedError('Not applicable to KeyEvent');
-  int get _pageY => throw new UnsupportedError('Not applicable to KeyEvent');
-  @Experimental() // untriaged
-  bool getModifierState(String keyArgument) => throw new UnimplementedError();
-  @Experimental() // untriaged
-  int get location => throw new UnimplementedError();
-  @Experimental() // untriaged
-  bool get repeat => throw new UnimplementedError();
-  dynamic get _get_view => throw new UnimplementedError();
 }
 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -38645,7 +38588,7 @@ class _Utils {
     // TODO(vsm): Move these checks into native code.
     ClassMirror cls = reflectClass(type);
     if (_isBuiltinType(cls)) {
-      throw new UnsupportedError("Invalid custom element from ${(cls.owner as LibraryMirror).uri}.");
+      throw new UnsupportedError("Invalid custom element from ${cls.owner.uri}.");
     }
     var className = MirrorSystem.getName(cls.simpleName);
     var createdConstructor = cls.declarations[new Symbol('$className.created')];
diff --git a/sdk/lib/html/html_common/lists.dart b/sdk/lib/html/html_common/lists.dart
index f33d64afb99..5c230a971d3 100644
--- a/sdk/lib/html/html_common/lists.dart
+++ b/sdk/lib/html/html_common/lists.dart
@@ -70,6 +70,6 @@ class Lists {
 /**
  * For accessing underlying node lists, for dart:js interop.
  */
-abstract class NodeListWrapper {
+class NodeListWrapper {
   List<Node> get rawList;
 }
diff --git a/tests/compiler/dart2js/analyze_api_test.dart b/tests/compiler/dart2js/analyze_api_test.dart
index 8afa974694b..2e860d55cec 100644
--- a/tests/compiler/dart2js/analyze_api_test.dart
+++ b/tests/compiler/dart2js/analyze_api_test.dart
@@ -22,6 +22,11 @@ import "package:async_helper/async_helper.dart";
 const Map<String, List<String>> WHITE_LIST = const {
   'html_dart2js.dart': const [
       "doesn't implement", // Issue 16105.
+      "is not assignable to the type 'HtmlCollection'", // Issue 16105.
+      "is not a subtype of the overridden method type", // Issue 16105.
+  ],
+  'html_common/lists.dart': const [
+      "has no implementation" // Issue 16105.
   ],
 };
 
diff --git a/tools/dom/dom.json b/tools/dom/dom.json
index 843b113cfcd..e9576fae7ee 100644
--- a/tools/dom/dom.json
+++ b/tools/dom/dom.json
@@ -2241,8 +2241,6 @@
         "support_level": "nonstandard"
       },
       "inputMethodContext": {
-        "comment": "http://www.w3.org/TR/ime-api/#the-inputmethodcontext-property Per the spec is only on HTMLElement.",
-        "dart_action": "suppress",
         "support_level": "untriaged"
       },
       "insertAdjacentElement": {
@@ -3382,6 +3380,7 @@
       },
       "origin": {
         "comment": "WebKit only",
+        "dart_action": "suppress",
         "support_level": "nonstandard"
       },
       "password": {
diff --git a/tools/dom/scripts/htmlrenamer.py b/tools/dom/scripts/htmlrenamer.py
index 9d848f73e85..be8372a27d9 100644
--- a/tools/dom/scripts/htmlrenamer.py
+++ b/tools/dom/scripts/htmlrenamer.py
@@ -627,7 +627,6 @@ removed_html_members = monitored.Set('htmlrenamer.removed_html_members', [
     'HTMLDirectoryElement.*',
     'HTMLDivElement.align',
     'HTMLFontElement.*',
-    'HTMLFormControlsCollection.__getter__',
     'HTMLFormElement.get:elements',
     'HTMLFrameElement.*',
     'HTMLFrameSetElement.*',
@@ -754,7 +753,6 @@ removed_html_members = monitored.Set('htmlrenamer.removed_html_members', [
     'SVGElementInstance.on:wheel',
     'WheelEvent.wheelDelta',
     'Window.on:wheel',
-    'WindowEventHandlers.on:beforeUnload',
     'WorkerGlobalScope.webkitIndexedDB',
 # TODO(jacobr): should these be removed?
     'Document.close',
diff --git a/tools/dom/scripts/systemnative.py b/tools/dom/scripts/systemnative.py
index 74f61df54a2..36f73cc1951 100644
--- a/tools/dom/scripts/systemnative.py
+++ b/tools/dom/scripts/systemnative.py
@@ -1382,7 +1382,6 @@ class CPPLibraryEmitter():
     is_node_test = lambda interface: interface.id == 'Node'
     is_active_test = lambda interface: 'ActiveDOMObject' in interface.ext_attrs
     is_event_target_test = lambda interface: 'EventTarget' in interface.ext_attrs
-
     def TypeCheckHelper(test):
       return 'true' if any(map(test, database.Hierarchy(interface))) else 'false'
     for interface in database.GetInterfaces():
diff --git a/tools/dom/src/CrossFrameTypes.dart b/tools/dom/src/CrossFrameTypes.dart
index 6adfca0be34..cda5957dd8f 100644
--- a/tools/dom/src/CrossFrameTypes.dart
+++ b/tools/dom/src/CrossFrameTypes.dart
@@ -23,7 +23,7 @@ part of html;
  * * [DOM Window](https://developer.mozilla.org/en-US/docs/DOM/window) from MDN.
  * * [Window](http://www.w3.org/TR/Window/) from the W3C.
  */
-abstract class WindowBase {
+abstract class WindowBase implements EventTarget {
   // Fields.
 
   /**
diff --git a/tools/dom/src/EventStreamProvider.dart b/tools/dom/src/EventStreamProvider.dart
index ea66285cf2d..85b4d78cb38 100644
--- a/tools/dom/src/EventStreamProvider.dart
+++ b/tools/dom/src/EventStreamProvider.dart
@@ -428,7 +428,4 @@ class _CustomEventStreamProvider<T extends Event>
   String getEventType(EventTarget target) {
     return _eventTypeGetter(target);
   }
-
-  String get _eventType =>
-      throw new UnsupportedError('Access type through getEventType method.');
 }
diff --git a/tools/dom/src/WrappedEvent.dart b/tools/dom/src/WrappedEvent.dart
index 4f30af92cc2..af64faed5b8 100644
--- a/tools/dom/src/WrappedEvent.dart
+++ b/tools/dom/src/WrappedEvent.dart
@@ -9,10 +9,6 @@ part of dart.html;
  */
 class _WrappedEvent implements Event {
   final Event wrapped;
-
-  /** The CSS selector involved with event delegation. */
-  String _selector;
-
   _WrappedEvent(this.wrapped);
 
   bool get bubbles => wrapped.bubbles;
@@ -50,41 +46,4 @@ class _WrappedEvent implements Event {
   void stopPropagation() {
     wrapped.stopPropagation();
   }
-
-  /**
-   * A pointer to the element whose CSS selector matched within which an event
-   * was fired. If this Event was not associated with any Event delegation,
-   * accessing this value will throw an [UnsupportedError].
-   */
-  Element get matchingTarget {
-    if (_selector == null) {
-      throw new UnsupportedError('Cannot call matchingTarget if this Event did'
-          ' not arise as a result of event delegation.');
-    }
-    var currentTarget = this.currentTarget;
-    var target = this.target;
-    var matchedTarget;
-    do {
-      if (target.matches(_selector)) return target;
-      target = target.parent;
-    } while (target != null && target != currentTarget.parent);
-    throw new StateError('No selector matched for populating matchedTarget.');
-  }
-
-  /**
-   * This event's path, taking into account shadow DOM.
-   *
-   * ## Other resources
-   *
-   * * [Shadow DOM extensions to Event]
-   * (http://w3c.github.io/webcomponents/spec/shadow/#extensions-to-event) from
-   * W3C.
-   */
-  // https://dvcs.w3.org/hg/webcomponents/raw-file/tip/spec/shadow/index.html#extensions-to-event
-  @Experimental()
-  List<Node> get path => wrapped.path;
-
-  dynamic get _get_currentTarget => wrapped._get_currentTarget;
-
-  dynamic get _get_target => wrapped._get_target;
 }
diff --git a/tools/dom/src/dart2js_KeyEvent.dart b/tools/dom/src/dart2js_KeyEvent.dart
index f3be576c6e5..8c7b5fd6d67 100644
--- a/tools/dom/src/dart2js_KeyEvent.dart
+++ b/tools/dom/src/dart2js_KeyEvent.dart
@@ -210,15 +210,4 @@ class KeyEvent extends _WrappedEvent implements KeyboardEvent {
     throw new UnsupportedError(
         "Cannot initialize a KeyboardEvent from a KeyEvent.");
   }
-  int get _layerX => throw new UnsupportedError('Not applicable to KeyEvent');
-  int get _layerY => throw new UnsupportedError('Not applicable to KeyEvent');
-  int get _pageX => throw new UnsupportedError('Not applicable to KeyEvent');
-  int get _pageY => throw new UnsupportedError('Not applicable to KeyEvent');
-  @Experimental() // untriaged
-  bool getModifierState(String keyArgument) => throw new UnimplementedError();
-  @Experimental() // untriaged
-  int get location => throw new UnimplementedError();
-  @Experimental() // untriaged
-  bool get repeat => throw new UnimplementedError();
-  dynamic get _get_view => throw new UnimplementedError();
 }
diff --git a/tools/dom/src/dartium_KeyEvent.dart b/tools/dom/src/dartium_KeyEvent.dart
index d3716b39be8..830da2f4424 100644
--- a/tools/dom/src/dartium_KeyEvent.dart
+++ b/tools/dom/src/dartium_KeyEvent.dart
@@ -129,15 +129,4 @@ class KeyEvent extends _WrappedEvent implements KeyboardEvent {
     throw new UnsupportedError(
         "Cannot initialize a KeyboardEvent from a KeyEvent.");
   }
-  int get _layerX => throw new UnsupportedError('Not applicable to KeyEvent');
-  int get _layerY => throw new UnsupportedError('Not applicable to KeyEvent');
-  int get _pageX => throw new UnsupportedError('Not applicable to KeyEvent');
-  int get _pageY => throw new UnsupportedError('Not applicable to KeyEvent');
-  @Experimental() // untriaged
-  bool getModifierState(String keyArgument) => throw new UnimplementedError();
-  @Experimental() // untriaged
-  int get location => throw new UnimplementedError();
-  @Experimental() // untriaged
-  bool get repeat => throw new UnimplementedError();
-  dynamic get _get_view => throw new UnimplementedError();
 }
diff --git a/tools/dom/src/native_DOMImplementation.dart b/tools/dom/src/native_DOMImplementation.dart
index d84e39642d2..d7a3fe654b3 100644
--- a/tools/dom/src/native_DOMImplementation.dart
+++ b/tools/dom/src/native_DOMImplementation.dart
@@ -406,7 +406,7 @@ class _Utils {
     // TODO(vsm): Move these checks into native code.
     ClassMirror cls = reflectClass(type);
     if (_isBuiltinType(cls)) {
-      throw new UnsupportedError("Invalid custom element from ${(cls.owner as LibraryMirror).uri}.");
+      throw new UnsupportedError("Invalid custom element from ${cls.owner.uri}.");
     }
     var className = MirrorSystem.getName(cls.simpleName);
     var createdConstructor = cls.declarations[new Symbol('$className.created')];
diff --git a/tools/dom/templates/html/impl/impl_AbstractWorker.darttemplate b/tools/dom/templates/html/impl/impl_AbstractWorker.darttemplate
index e23390d758a..2349ce5e3dc 100644
--- a/tools/dom/templates/html/impl/impl_AbstractWorker.darttemplate
+++ b/tools/dom/templates/html/impl/impl_AbstractWorker.darttemplate
@@ -5,5 +5,5 @@
 part of $LIBRARYNAME;
 
 @DocsEditable()
-$(ANNOTATIONS)$(CLASS_MODIFIERS)abstract class $CLASSNAME$EXTENDS$MIXINS implements EventTarget$NATIVESPEC {
+$(ANNOTATIONS)$(CLASS_MODIFIERS)class $CLASSNAME$EXTENDS$MIXINS implements EventTarget$NATIVESPEC {
 $!MEMBERS}
diff --git a/tools/dom/templates/html/impl/impl_DocumentFragment.darttemplate b/tools/dom/templates/html/impl/impl_DocumentFragment.darttemplate
index 86db4ea331b..e57d98ff6ad 100644
--- a/tools/dom/templates/html/impl/impl_DocumentFragment.darttemplate
+++ b/tools/dom/templates/html/impl/impl_DocumentFragment.darttemplate
@@ -21,21 +21,18 @@ $(ANNOTATIONS)$(CLASS_MODIFIERS)class $CLASSNAME$EXTENDS$IMPLEMENTS$NATIVESPEC {
         validator: validator, treeSanitizer: treeSanitizer);
   }
 
-  HtmlCollection get _children => throw new UnimplementedError(
-      'Use _docChildren instead');
-
 $if DART2JS
   // Native field is used only by Dart code so does not lead to instantiation
   // of native classes
   @Creates('Null')
 $endif
-  List<Element> _docChildren;
+  List<Element> _children;
 
   List<Element> get children {
-    if (_docChildren == null) {
-      _docChildren = new FilteredElementList(this);
+    if (_children == null) {
+      _children = new FilteredElementList(this);
     }
-    return _docChildren;
+    return _children;
   }
 
   void set children(List<Element> value) {
diff --git a/tools/dom/templates/html/impl/impl_Window.darttemplate b/tools/dom/templates/html/impl/impl_Window.darttemplate
index cdf44bf52b6..b84bb5f3fa4 100644
--- a/tools/dom/templates/html/impl/impl_Window.darttemplate
+++ b/tools/dom/templates/html/impl/impl_Window.darttemplate
@@ -394,13 +394,4 @@ $endif
   String getEventType(EventTarget target) {
     return _eventType;
   }
-
-  ElementStream<BeforeUnloadEvent> forElement(Element e, {bool useCapture: false}) {
-    return new _ElementEventStreamImpl(e, _eventType, useCapture);
-  }
-
-  ElementStream<BeforeUnloadEvent> _forElementList(ElementList e,
-      {bool useCapture: false}) {
-    return new _ElementListEventStreamImpl(e, _eventType, useCapture);
-  }
 }