Support custom V8 bindings on WebWorker threads (issue #451).

- Add CefRenderProcessHandler callbacks for WebWorker context creation, release and uncaught exceptions.
- Add CefTaskRunner class that supports posting of tasks to standard threads and WebWorker threads.
- Organize V8 internal state information on a per-thread/per-Isolate basis.
- Add webkit_451.patch that provides the WebKit implementation.

git-svn-id: https://chromiumembedded.googlecode.com/svn/trunk@972 5089003a-bbd8-11dd-ad1f-f1f9622dbc98

tests/unittests/test_handler.h

@@ -1,4 +1,4 @@
-// Copyright (c) 2011 The Chromium Embedded Framework Authors. All rights
+// Copyright (c) 2013 The Chromium Embedded Framework Authors. All rights
 // reserved. Use of this source code is governed by a BSD-style license that
 // can be found in the LICENSE file.
 
@@ -123,6 +123,7 @@ class TestHandler : public CefClient,
 // Post a task to the specified thread and wait for the task to execute as
 // indication that all previously pending tasks on that thread have completed.
 void WaitForThread(CefThreadId thread_id);
+void WaitForThread(CefRefPtr<CefTaskRunner> task_runner);
 
 #define WaitForIOThread() WaitForThread(TID_IO)
 #define WaitForUIThread() WaitForThread(TID_UI)