Fix various warnings and errors in html_diff and its annotations.

client/html/release/html.dart

Index: client/html/release/html.dart
diff --git a/client/html/release/html.dart b/client/html/release/html.dart
index acf7b8bb24e34afab643aac77761222c41444ca3..86dc8be9ae441fc00741af8cd7105dc5171199c2 100644
--- a/client/html/release/html.dart
+++ b/client/html/release/html.dart
@@ -3642,18 +3642,6 @@ interface Location {
 
 // WARNING: Do not edit - generated code.
 
-interface LoseContext {
-
-  void loseContext();
-
-  void restoreContext();
-}
-// Copyright (c) 2011, 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.
-
 interface LowPass2FilterNode extends AudioNode {
 
   AudioParam get cutoff();
@@ -12398,6 +12386,16 @@ interface KeyName {
 // 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.
 
+interface LoseContext {
+
+  void loseContext();
+
+  void restoreContext();
+}
+// Copyright (c) 2011, 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.
+
 interface MessageEvent extends Event default MessageEventWrappingImplementation {
 
   MessageEvent(String type, String data, String origin, String lastEventId,