Some changes to improve precision of types in dart:html

sdk/lib/html/dart2js/html_dart2js.dart

 library html;
 
 import 'dart:isolate';
 import 'dart:json';
 // 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
 // BSD-style license that can be found in the LICENSE file.
 
 // DO NOT EDIT
 // Auto-generated dart:html library.
@@ skipping 4197 matching lines @@
     }
     return _Elements.createCanvasElement(width, height);
   }
 
   /** @domName HTMLCanvasElement.height */
   int height;
 
   /** @domName HTMLCanvasElement.width */
   int width;
 
-  /** @domName HTMLCanvasElement.getContext */
-  Object getContext(String contextId) native;
-
   /** @domName HTMLCanvasElement.toDataURL */
   String toDataURL(String type, [num quality]) native;
 
 
+  CanvasRenderingContext getContext(String contextId) native;
   CanvasRenderingContext2D get context2d => getContext('2d');
 }
 
 /// @domName CanvasGradient
 class CanvasGradient native "*CanvasGradient" {
 
   /** @domName CanvasGradient.addColorStop */
   void addColorStop(num offset, String color) native;
 }
 
@@ skipping 8322 matching lines @@
            'subtree': true,
            'attributeOldValue': true,
            'characterDataOldValue': true };
 
 
   static _createDict() => JS('var', '{}');
   static _add(m, String key, value) { JS('void', '#[#] = #', m, key, value); }
   static _fixupList(list) => list;  // TODO: Ensure is a JavaScript Array.
 
   // Call native function with no conversions.
-  _call(target, options) native 'observe';
+  void _call(target, options) native 'observe';
 }
 
 /// @domName MutationRecord
 class MutationRecord native "*MutationRecord" {
 
   /** @domName MutationRecord.addedNodes */
   final List<Node> addedNodes;
 
   /** @domName MutationRecord.attributeName */
   final String attributeName;
@@ skipping 1479 matching lines @@
 
   /** @domName WebKitPoint.y */
   num y;
 
 }
 
 /// @domName PopStateEvent
 class PopStateEvent extends Event native "*PopStateEvent" {
 
   /** @domName PopStateEvent.state */
-  final Object state;
+  dynamic get state => _convertNativeToDart_SerializedScriptValue(this._state);
+  dynamic get _state => JS("dynamic", "#.state", this);
 }
 // 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
 // BSD-style license that can be found in the LICENSE file.
 
 // WARNING: Do not edit - generated code.
 
 
 typedef void PositionCallback(Geoposition position);
 
@@ skipping 14725 matching lines @@
     if (length < 0) throw new ArgumentError('length');
     if (start < 0) throw new RangeError.value(start);
     int end = start + length;
     if (end > a.length) throw new RangeError.value(end);
     for (int i = start; i < end; i++) {
       accumulator.add(a[i]);
     }
     return accumulator;
   }
 }