Fix various warnings and errors in html_diff and its annotations.

client/html/generated/src/wrapping/_LoseContextWrappingImplementation.dart

Index: client/html/generated/src/wrapping/_LoseContextWrappingImplementation.dart
diff --git a/client/html/generated/src/wrapping/_LoseContextWrappingImplementation.dart b/client/html/generated/src/wrapping/_LoseContextWrappingImplementation.dart
deleted file mode 100644
index 281d7e87d74a5b8900397c65dc59d73b35fe385f..0000000000000000000000000000000000000000
--- a/client/html/generated/src/wrapping/_LoseContextWrappingImplementation.dart
+++ /dev/null
@@ -1,19 +0,0 @@
-// 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.
-
-class LoseContextWrappingImplementation extends DOMWrapperBase implements LoseContext {
-  LoseContextWrappingImplementation._wrap(ptr) : super._wrap(ptr) {}
-
-  void loseContext() {
-    _ptr.loseContext();
-    return;
-  }
-
-  void restoreContext() {
-    _ptr.restoreContext();
-    return;
-  }
-}