Introduce FlexibleArrayBufferView and TypedFlexibleArrayBufferView

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 2255 matching lines @@
             'dom/ElementRareData.cpp',
             'dom/ElementRareData.h',
             'dom/ElementTraversal.h',
             'dom/EmptyNodeList.cpp',
             'dom/EmptyNodeList.h',
             'dom/ExecutionContext.cpp',
             'dom/ExecutionContext.h',
             'dom/ExecutionContextTask.h',
             'dom/FirstLetterPseudoElement.cpp',
             'dom/FirstLetterPseudoElement.h',
+            'dom/FlexibleArrayBufferView.h',
             'dom/FrameRequestCallback.h',
             'dom/FrameRequestCallbackCollection.cpp',
             'dom/FrameRequestCallbackCollection.h',
             'dom/Fullscreen.cpp',
             'dom/Fullscreen.h',
             'dom/GlobalEventHandlers.h',
             'dom/IconURL.cpp',
             'dom/IconURL.h',
             'dom/IdTargetObserver.cpp',
             'dom/IdTargetObserver.h',
@@ skipping 1529 matching lines @@
             'style/OutlineValueTest.cpp',
             'style/SVGComputedStyleTest.cpp',
             'svg/UnsafeSVGAttributeSanitizationTest.cpp',
             'testing/PrivateScriptTestTest.cpp',
             'timing/MemoryInfoTest.cpp',
             'workers/WorkerThreadTest.cpp',
             'xml/parser/SharedBufferReaderTest.cpp',
         ],
     }
 }