Merging dart:html interfaces and implementations

lib/html/templates/html/impl/impl_WebSocket.darttemplate

Index: lib/html/templates/html/impl/impl_WebSocket.darttemplate
diff --git a/lib/html/templates/html/impl/impl_CanvasElement.darttemplate b/lib/html/templates/html/impl/impl_WebSocket.darttemplate
similarity index 68%
copy from lib/html/templates/html/impl/impl_CanvasElement.darttemplate
copy to lib/html/templates/html/impl/impl_WebSocket.darttemplate
index 7d9d2bf641df249a2bae9fbae72e51bd3f115399..2c2ef599e69b01bd9d80a4cd3b2a2a5147852777 100644
--- a/lib/html/templates/html/impl/impl_CanvasElement.darttemplate
+++ b/lib/html/templates/html/impl/impl_WebSocket.darttemplate
@@ -2,8 +2,9 @@
 // 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.
+
 class $CLASSNAME$EXTENDS$IMPLEMENTS$NATIVESPEC {
+  factory $CLASSNAME(String url) => _$(CLASSNAME)FactoryProvider.create$CLASSNAME(url);
 $!MEMBERS
-
-  CanvasRenderingContext2D get context2d => getContext('2d');
 }