Added the CanvasImageSource interface, which all types that a canvas can draw

tools/dom/templates/html/dartium/html_dartium.darttemplate

 // 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.
 
 /// The Dart HTML library.
 library dart.dom.html;
 
 import 'dart:async';
 import 'dart:collection';
 import 'dart:html_common';
 import 'dart:indexed_db';
 import 'dart:isolate';
 import 'dart:json' as json;
 import 'dart:math';
 import 'dart:nativewrappers';
 import 'dart:typeddata' as _typeddata;
 import 'dart:web_sql';
 // Not actually used, but imported since dart:html can generate these objects.
 import 'dart:svg' as svg;
 import 'dart:web_audio' as web_audio;
 
 $!GENERATED_DART_FILES
 
 part '$AUXILIARY_DIR/AttributeMap.dart';
+part '$AUXILIARY_DIR/CanvasImageSource.dart';
 part '$AUXILIARY_DIR/CrossFrameTypes.dart';
 part '$AUXILIARY_DIR/CssClassSet.dart';
 part '$AUXILIARY_DIR/EventListener.dart';
 part '$AUXILIARY_DIR/EventStreamProvider.dart';
 part '$AUXILIARY_DIR/KeyboardEventController.dart';
 part '$AUXILIARY_DIR/KeyCode.dart';
 part '$AUXILIARY_DIR/KeyLocation.dart';
 part '$AUXILIARY_DIR/KeyName.dart';
 part '$AUXILIARY_DIR/Point.dart';
 part '$AUXILIARY_DIR/ReadyState.dart';
@@ skipping 47 matching lines @@
       _callPortLastResult = json.parse(_getPortSyncEventData(event));
     });
     _callPortInitialized = true;
   }
   assert(_callPortLastResult == null);
   _dispatchEvent('js-sync-message', {'id': id, 'message': message});
   var result = _callPortLastResult;
   _callPortLastResult = null;
   return result;
 }