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

libcef_dll/cpptoc/task_cpptoc.cc

@@ -15,8 +15,7 @@
 
 // MEMBER FUNCTIONS - Body may be edited by hand.
 
-void CEF_CALLBACK task_execute(struct _cef_task_t* self,
-    cef_thread_id_t threadId) {
+void CEF_CALLBACK task_execute(struct _cef_task_t* self) {
   // AUTO-GENERATED CONTENT - DELETE THIS COMMENT BEFORE MODIFYING
 
   DCHECK(self);
@@ -24,8 +23,7 @@ void CEF_CALLBACK task_execute(struct _cef_task_t* self,
     return;
 
   // Execute
-  CefTaskCppToC::Get(self)->Execute(
-      threadId);
+  CefTaskCppToC::Get(self)->Execute();
 }