[Worklets] Add basic debugging to main thread worklets.

third_party/WebKit/Source/core/core.gypi

 {
     'includes': [
         'core_generated.gypi',
     ],
     'variables': {
         # Files for which bindings (.cpp and .h files) will be generated
         'core_idl_files': [
             'animation/KeyframeEffect.idl',
             'animation/EffectModel.idl',
             'animation/AnimationEffectReadOnly.idl',
@@ skipping 2190 matching lines @@
             'workers/AbstractWorker.cpp',
             'workers/AbstractWorker.h',
             'workers/DedicatedWorkerGlobalScope.cpp',
             'workers/DedicatedWorkerGlobalScope.h',
             'workers/DedicatedWorkerMessagingProxy.cpp',
             'workers/DedicatedWorkerMessagingProxy.h',
             'workers/DedicatedWorkerThread.cpp',
             'workers/DedicatedWorkerThread.h',
             'workers/InProcessWorkerBase.cpp',
             'workers/InProcessWorkerBase.h',
+            'workers/MainThreadWorkletGlobalScope.h',
             'workers/SharedWorker.cpp',
             'workers/SharedWorker.h',
             'workers/SharedWorkerGlobalScope.cpp',
             'workers/SharedWorkerGlobalScope.h',
             'workers/SharedWorkerRepositoryClient.h',
             'workers/SharedWorkerThread.cpp',
             'workers/SharedWorkerThread.h',
             'workers/Worker.cpp',
             'workers/Worker.h',
             'workers/WorkerClients.h',
@@ skipping 1842 matching lines @@
             'style/SVGComputedStyleTest.cpp',
             'svg/SVGPathParserTest.cpp',
             'svg/UnsafeSVGAttributeSanitizationTest.cpp',
             'testing/PrivateScriptTestTest.cpp',
             'timing/MemoryInfoTest.cpp',
             'workers/WorkerThreadTest.cpp',
             'xml/parser/SharedBufferReaderTest.cpp',
         ],
     }
 }