Remove Dart 2 errors in package:js_ast

Change-Id: I1684a662bb777e2175cb0f1a6590136ab3ba5cc2
Reviewed-on: https://dart-review.googlesource.com/48580
Reviewed-by: Stephen Adams <sra@google.com>

pkg/js_ast/lib/src/builder.dart

@@ -466,7 +466,7 @@ class JsBuilder {
   }
 
   Iterable<Literal> joinLiterals(Iterable<Literal> list, Literal separator) {
-    return new _InterleaveIterable(list, separator);
+    return new _InterleaveIterable<Literal>(list, separator);
   }
 
   LiteralString quoteName(Name name, {allowNull: false}) {
@@ -1574,9 +1574,9 @@ class MiniJsParser {
   }
 }
 
-class _InterleaveIterator implements Iterator<Node> {
-  Iterator<Node> source;
-  Node separator;
+class _InterleaveIterator<T extends Node> implements Iterator<T> {
+  Iterator<T> source;
+  T separator;
   bool isNextSeparator = false;
   bool isInitialized = false;
 
@@ -1594,19 +1594,19 @@ class _InterleaveIterator implements Iterator<Node> {
     }
   }
 
-  Node get current {
+  T get current {
     if (isNextSeparator) return separator;
     return source.current;
   }
 }
 
-class _InterleaveIterable extends IterableBase {
-  Iterable<Node> source;
-  Node separator;
+class _InterleaveIterable<T extends Node> extends IterableBase<T> {
+  Iterable<T> source;
+  T separator;
 
   _InterleaveIterable(this.source, this.separator);
 
-  Iterator<Node> get iterator {
-    return new _InterleaveIterator(source.iterator, separator);
+  Iterator<T> get iterator {
+    return new _InterleaveIterator<T>(source.iterator, separator);
   }
 }

pkg/js_ast/lib/src/nodes.dart

@@ -979,6 +979,8 @@ abstract class Name extends Literal
   R accept1<R, A>(NodeVisitor1<R, A> visitor, A arg) =>
       visitor.visitName(this, arg);
 
+  Name _clone();
+
   /// Returns a unique [key] for this name.
   ///
   /// The key is unrelated to the actual name and is not intended for human

pkg/js_ast/lib/src/printer.dart

@@ -1297,7 +1297,7 @@ class DanglingElseVisitor extends BaseVisitor<bool> {
 
   bool visitProgram(Program node) => false;
 
-  bool visitNode(Statement node) {
+  bool visitNode(Node node) {
     context.error("Forgot node: $node");
     return null;
   }

pkg/js_ast/lib/src/template.dart

@@ -130,7 +130,7 @@ class Template {
  * trees. [arguments] is a List for positional templates, or Map for
  * named templates.
  */
-typedef Node Instantiator(var arguments);
+typedef /*Node|Iterable<Node>*/ Instantiator(var arguments);
 
 /**
  * InstantiatorGeneratorVisitor compiles a template.  This class compiles a tree
@@ -300,7 +300,8 @@ class InstantiatorGeneratorVisitor implements NodeVisitor<Instantiator> {
   }
 
   Instantiator visitProgram(Program node) {
-    List instantiators = node.body.map(visitSplayableStatement).toList();
+    List<Instantiator> instantiators =
+        node.body.map(visitSplayableStatement).toList();
     return (arguments) {
       List<Statement> statements = <Statement>[];
       void add(node) {
@@ -320,7 +321,8 @@ class InstantiatorGeneratorVisitor implements NodeVisitor<Instantiator> {
   }
 
   Instantiator visitBlock(Block node) {
-    List instantiators = node.statements.map(visitSplayableStatement).toList();
+    List<Instantiator> instantiators =
+        node.statements.map(visitSplayableStatement).toList();
     return (arguments) {
       List<Statement> statements = <Statement>[];
       void add(node) {