[web] deprecate dart:web_sql

The WebSql was dropped 5+ years ago and this library is unsupported.

This change adds the `@deprecated` annotation on the library and APIs in
dart:html that expose it (`window.openDatabase`). It also indicates to dartdoc
to skip it for the api.dart.dev site.

I run a `pub_crawl` process to verify that this is not in use. I checked 15K
packages, and only found 2 occurrances of an import to this library:
  * One in a package marked as discontinued (used for migrating constants back
  in Dart 2)
  * Another in an example mock test (generated by mockito for mocking dart:html)
Also no library uses `window.openDatabase` either.

We will send a breaking change announcement soon and plan to delete this in a
future Dart release (possibly 2.15).

Fixes https://github.com/dart-lang/sdk/issues/45687
Fixes https://github.com/dart-lang/sdk/issues/45688

Change-Id: I8cd2bfa0ce64892c3f108bd6e24b8a0a3ec7c6ed
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/196461
Reviewed-by: Srujan Gaddam <srujzs@google.com>
Commit-Queue: Sigmund Cherem <sigmund@google.com>

CHANGELOG.md

@@ -14,6 +14,17 @@
     daylight saving changes that are not precisely one hour.
     (No change on the Web which uses the JavaScript `Date` object.)
 
+#### `dart:web_sql`
+
+*   `dart:web_sql` is marked deprecated and will be removed in an upcoming
+    release. Also the API `window.openDatabase` in `dart:html` is deprecated as
+    well.
+
+    This API and library was exposing the WebSQL proposed standard. The standard
+    was abandoned more than 5 years ago and is not supported by most browsers.
+    The `dart:web_sql` library has been documented as unsupported and deprecated
+    for many years as well and but wasn't annotated properly until now.
+
 ### Dart VM
 
 *   **Breaking Change** [#45071][]: `Dart_NewWeakPersistentHandle`'s and

sdk/lib/html/dart2js/html_dart2js.dart

@@ -33660,6 +33660,7 @@ class Window extends EventTarget
   @SupportedBrowser(SupportedBrowser.CHROME)
   @SupportedBrowser(SupportedBrowser.SAFARI)
   @Creates('SqlDatabase')
+  @deprecated
   SqlDatabase openDatabase(
       String name, String version, String displayName, int estimatedSize,
       [DatabaseCallback? creationCallback]) {

sdk/lib/web_sql/dart2js/web_sql_dart2js.dart

@@ -9,6 +9,7 @@
  * The [dart:indexed_db] APIs is a recommended alternatives.
  *
  * {@category Web}
+ * {@nodoc}
  */
 library dart.dom.web_sql;
 
@@ -23,6 +24,7 @@ import 'dart:_interceptors' show Interceptor;
 // https://code.google.com/p/dart/wiki/ContributingHTMLDocumentation
 // Auto-generated dart:audio library.
 
+@deprecated
 import 'dart:_js_helper'
     show
         applyExtension,

tools/dom/templates/html/dart2js/web_sql_dart2js.darttemplate

@@ -13,7 +13,9 @@
  * The [dart:indexed_db] APIs is a recommended alternatives.
  *
  * {@category Web}
+ * {@nodoc}
  */
+@deprecated
 library dart.dom.web_sql;
 
 import 'dart:async';

tools/dom/templates/html/impl/impl_Window.darttemplate

@@ -226,6 +226,7 @@ $!MEMBERS
   @SupportedBrowser(SupportedBrowser.CHROME)
   @SupportedBrowser(SupportedBrowser.SAFARI)
   @Creates('SqlDatabase')
+  @deprecated
   SqlDatabase openDatabase(
       String name, String version, String displayName, int estimatedSize,
       [DatabaseCallback$NULLABLE creationCallback]) {