Expose the ServiceWorker's v8 context to embedders.

Source/web/WebEmbeddedWorkerImpl.cpp

Index: Source/web/WebEmbeddedWorkerImpl.cpp
diff --git a/Source/web/WebEmbeddedWorkerImpl.cpp b/Source/web/WebEmbeddedWorkerImpl.cpp
index 3c396de4c8341f4259073035c84d9491fdf29fff..a5d085e8834c6638966c17642cf42089190abc81 100644
--- a/Source/web/WebEmbeddedWorkerImpl.cpp
+++ b/Source/web/WebEmbeddedWorkerImpl.cpp
@@ -169,6 +169,12 @@ WebEmbeddedWorkerImpl::~WebEmbeddedWorkerImpl()
     m_mainFrame->close();
 }
 
+void WebEmbeddedWorkerImpl::postTask(PassOwnPtr<ExecutionContextTask> task)

[Jeffrey Yasskin, 2014/07/16 23:14:58]

This is again used by the test.

In Content, this purpose is served by
WorkerTaskRunner::PostTask(worker_thread_id), so it probably won't need to be
exposed from the Blink API. That mechanism works by recording all WorkerRunLoops
into a global variable in BlinkPlatformImpl::didStartWorkerRunLoop().

+{
+    // We don't propagate the bool return because |true| doesn't mean the task will be run.
+    m_workerThread->runLoop().postTask(task);
+}
+
 void WebEmbeddedWorkerImpl::startWorkerContext(
     const WebEmbeddedWorkerStartData& data)
 {