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

lib/html/dart2js/html_dart2js.dart

Index: lib/html/dart2js/html_dart2js.dart
diff --git a/lib/html/dart2js/html_dart2js.dart b/lib/html/dart2js/html_dart2js.dart
index 8dea02e5bc2ef041a587e7f8ecb16ca6676b336b..526f9b2445e338cd1764e351e5e98d835361b87b 100644
--- a/lib/html/dart2js/html_dart2js.dart
+++ b/lib/html/dart2js/html_dart2js.dart
@@ -38061,6 +38061,12 @@ 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;
@@ -38263,3 +38269,4 @@ class _Deserializer {
     throw "Unexpected serialized object";
   }
 }
+