Revert of Enable per thread heap on ServiceWorker

third_party/WebKit/Source/modules/serviceworkers/ServiceWorkerThread.cpp

 /*
  * Copyright (C) 2013 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 33 matching lines @@
   return wrapUnique(new ServiceWorkerThread(std::move(workerLoaderProxy),
                                             workerReportingProxy));
 }
 
 ServiceWorkerThread::ServiceWorkerThread(
     PassRefPtr<WorkerLoaderProxy> workerLoaderProxy,
     WorkerReportingProxy& workerReportingProxy)
     : WorkerThread(std::move(workerLoaderProxy), workerReportingProxy),
       m_workerBackingThread(
           WorkerBackingThread::create("ServiceWorker Thread",
-                                      BlinkGC::PerThreadHeapMode)) {}
+                                      BlinkGC::MainThreadHeapMode)) {}
 
 ServiceWorkerThread::~ServiceWorkerThread() {}
 
 void ServiceWorkerThread::clearWorkerBackingThread() {
   m_workerBackingThread = nullptr;
 }
 
 WorkerOrWorkletGlobalScope* ServiceWorkerThread::createWorkerGlobalScope(
     std::unique_ptr<WorkerThreadStartupData> startupData) {
   return ServiceWorkerGlobalScope::create(this, std::move(startupData));
 }
 
 }  // namespace blink