Revert of Enable per thread heap on DedicatedWorker

third_party/WebKit/Source/core/workers/DedicatedWorkerThread.cpp

Index: third_party/WebKit/Source/core/workers/DedicatedWorkerThread.cpp
diff --git a/third_party/WebKit/Source/core/workers/DedicatedWorkerThread.cpp b/third_party/WebKit/Source/core/workers/DedicatedWorkerThread.cpp
index 71d7f85ee1bcbdff45759637cd118103b4aa153f..105882ff32819d2b70437e65428a8463c0136806 100644
--- a/third_party/WebKit/Source/core/workers/DedicatedWorkerThread.cpp
+++ b/third_party/WebKit/Source/core/workers/DedicatedWorkerThread.cpp
@@ -1,3 +1,4 @@
+
 /*
  * Copyright (C) 2009 Google Inc. All rights reserved.
  *
@@ -54,7 +55,7 @@ DedicatedWorkerThread::DedicatedWorkerThread(
     : WorkerThread(std::move(workerLoaderProxy), workerObjectProxy),
       m_workerBackingThread(
           WorkerBackingThread::create("DedicatedWorker Thread",
-                                      BlinkGC::PerThreadHeapMode)),
+                                      BlinkGC::MainThreadHeapMode)),
       m_workerObjectProxy(workerObjectProxy),
       m_timeOrigin(timeOrigin) {}