Remove ArrayBufferDeallocationObserver

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 2160 matching lines @@
             'dom/CompositorProxy.h',
             'dom/ContainerNode.cpp',
             'dom/ContextFeatures.cpp',
             'dom/ContextFeatures.h',
             'dom/ContextLifecycleNotifier.cpp',
             'dom/ContextLifecycleNotifier.h',
             'dom/ContextLifecycleObserver.h',
             'dom/CrossThreadTask.h',
             'dom/DOMArrayBuffer.cpp',
             'dom/DOMArrayBuffer.h',
-            'dom/DOMArrayBufferDeallocationObserver.cpp',
-            'dom/DOMArrayBufferDeallocationObserver.h',
             'dom/DOMArrayBufferView.h',
             'dom/DOMArrayPiece.cpp',
             'dom/DOMArrayPiece.h',
             'dom/DOMDataView.cpp',
             'dom/DOMDataView.h',
             'dom/DOMError.cpp',
             'dom/DOMError.h',
             'dom/DOMException.cpp',
             'dom/DOMException.h',
             'dom/DOMImplementation.cpp',
@@ skipping 1744 matching lines @@
             'style/OutlineValueTest.cpp',
             'style/SVGComputedStyleTest.cpp',
             'svg/UnsafeSVGAttributeSanitizationTest.cpp',
             'testing/PrivateScriptTestTest.cpp',
             'timing/MemoryInfoTest.cpp',
             'workers/WorkerThreadTest.cpp',
             'xml/parser/SharedBufferReaderTest.cpp',
         ],
     }
 }