Revert of Change WokerThread to use a blink::WebThread.

Source/core/core.gypi

 {
     'includes': [
       'core_generated.gypi',
     ],
     'variables': {
         # Files for which bindings (.cpp and .h files) will be generated
         'core_idl_files': [
             'animation/Animation.idl',
             'animation/AnimationEffect.idl',
             'animation/AnimationPlayer.idl',
@@ skipping 1816 matching lines @@
             'workers/WorkerGlobalScopeProxyProvider.h',
             'workers/WorkerLoaderProxy.h',
             'workers/WorkerLocation.h',
             'workers/WorkerMessagingProxy.cpp',
             'workers/WorkerMessagingProxy.h',
             'workers/WorkerNavigator.cpp',
             'workers/WorkerNavigator.h',
             'workers/WorkerObjectProxy.cpp',
             'workers/WorkerObjectProxy.h',
             'workers/WorkerReportingProxy.h',
+            'workers/WorkerRunLoop.cpp',
             'workers/WorkerScriptLoader.cpp',
             'workers/WorkerScriptLoader.h',
             'workers/WorkerScriptLoaderClient.h',
             'workers/WorkerThread.cpp',
             'workers/WorkerThreadStartupData.cpp',
             'workers/WorkerThreadStartupData.h',
             'xml/DOMParser.cpp',
             'xml/DOMParser.h',
             'xml/DocumentXPathEvaluator.cpp',
             'xml/DocumentXPathEvaluator.h',
@@ skipping 1593 matching lines @@
             'rendering/RenderTableCellTest.cpp',
             'rendering/RenderTableRowTest.cpp',
             'rendering/shapes/BoxShapeTest.cpp',
             'testing/PrivateScriptTestTest.cpp',
             'testing/UnitTestHelpers.cpp',
             'testing/UnitTestHelpers.h',
             'xml/parser/SharedBufferReaderTest.cpp',
         ],
     }
 }