Seperate DOMVisualViewport from Blink's VisualViewport class

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 1701 matching lines @@
             'fileapi/FileReaderSync.cpp',
             'fileapi/FileReaderSync.h',
             'fileapi/URLFileAPI.cpp',
             'fileapi/URLFileAPI.h',
             'frame/BarProp.cpp',
             'frame/BarProp.h',
             'frame/DOMTimer.cpp',
             'frame/DOMTimer.h',
             'frame/DOMTimerCoordinator.cpp',
             'frame/DOMTimerCoordinator.h',
+            'frame/DOMVisualViewport.cpp',
+            'frame/DOMVisualViewport.h',
             'frame/DOMWindow.cpp',
             'frame/DOMWindow.h',
             'frame/DOMWindowBase64.cpp',
             'frame/DOMWindowBase64.h',
             'frame/DOMWindowEventHandlers.h',
             'frame/DOMWindowLifecycleNotifier.cpp',
             'frame/DOMWindowLifecycleNotifier.h',
             'frame/DOMWindowLifecycleObserver.h',
             'frame/DOMWindowProperty.cpp',
             'frame/DOMWindowProperty.h',
@@ skipping 2452 matching lines @@
             'testing/PrivateScriptTestTest.cpp',
             'timing/MemoryInfoTest.cpp',
             'timing/PerformanceBaseTest.cpp',
             'timing/PerformanceObserverTest.cpp',
             'workers/WorkerThreadTest.cpp',
             'workers/WorkerThreadTestHelper.h',
             'xml/parser/SharedBufferReaderTest.cpp',
         ],
     }
 }