Re-apply 'Unify dart:isolate.' with fixes for autogenerated dart2js and dartium html files.

lib/html/dartium/html_dartium.dart

Index: lib/html/dartium/html_dartium.dart
diff --git a/lib/html/dartium/html_dartium.dart b/lib/html/dartium/html_dartium.dart
index 6edcdfa5c3453ddaf7a0587c3c6302f581728fd0..bf35306cab4347117001e7372fec6a16eeb30eb9 100644
--- a/lib/html/dartium/html_dartium.dart
+++ b/lib/html/dartium/html_dartium.dart
@@ -41270,6 +41270,12 @@ class _Lists {
 // 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.
 
+// Patch file for the dart:isolate library.
+
+/********************************************************
+  Inserted from lib/isolate/serialization.dart
+ ********************************************************/
+
 class _MessageTraverserVisitedMap {
 
   operator[](var object) => null;
@@ -41472,6 +41478,7 @@ class _Deserializer {
     throw "Unexpected serialized object";
   }
 }
+
 // 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.