Revert of compositor-worker: Share a thread and an isolate for compositor workers.

Source/modules/InitModules.cpp

 // Copyright (c) 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "config.h"
 #include "InitModules.h"
 
 #include "bindings/modules/v8/ModuleBindingsInitializer.h"
 #include "core/EventTypeNames.h"
 #include "core/dom/Document.h"
 #include "modules/EventModulesFactory.h"
 #include "modules/EventModulesNames.h"
 #include "modules/EventTargetModulesNames.h"
 #include "modules/IndexedDBNames.h"
 #include "modules/accessibility/AXObjectCacheImpl.h"
-#include "modules/compositorworker/CompositorWorkerManager.h"
 #include "modules/filesystem/DraggedIsolatedFileSystemImpl.h"
 #include "modules/webdatabase/DatabaseManager.h"
 
 namespace blink {
 
 void ModulesInitializer::init()
 {
     ASSERT(!isInitialized());
 
     // Strings must be initialized before calling CoreInitializer::init().
     EventNames::initModules();
     EventTargetNames::initModules();
     Document::registerEventFactory(EventModulesFactory::create());
     ModuleBindingsInitializer::init();
     IndexedDBNames::init();
     AXObjectCache::init(AXObjectCacheImpl::create);
     DraggedIsolatedFileSystem::init(DraggedIsolatedFileSystemImpl::prepareForDataObject);
 
     CoreInitializer::init();
 
-    if (RuntimeEnabledFeatures::compositorWorkerEnabled())
-        CompositorWorkerManager::initialize();
-
     ASSERT(isInitialized());
 }
 
 void ModulesInitializer::terminateThreads()
 {
-    if (RuntimeEnabledFeatures::compositorWorkerEnabled())
-        CompositorWorkerManager::shutdown();
     DatabaseManager::terminateDatabaseThread();
 }
 
 } // namespace blink