Remove the (already disabled) OverflowChangedEvent runtime flag

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 95 matching lines @@
             'events/CompositionEvent.idl',
             'events/CustomEvent.idl',
             'events/ErrorEvent.idl',
             'events/Event.idl',
             'events/EventTarget.idl',
             'events/FocusEvent.idl',
             'events/HashChangeEvent.idl',
             'events/KeyboardEvent.idl',
             'events/MessageEvent.idl',
             'events/MutationEvent.idl',
-            'events/OverflowEvent.idl',
             'events/PageTransitionEvent.idl',
             'events/PointerEvent.idl',
             'events/PopStateEvent.idl',
             'events/ProgressEvent.idl',
             'events/PromiseRejectionEvent.idl',
             'events/RelatedEvent.idl',
             'events/ResourceProgressEvent.idl',
             'events/SecurityPolicyViolationEvent.idl',
             'events/TextEvent.idl',
             'events/TouchEvent.idl',
@@ skipping 341 matching lines @@
             'events/CompositionEvent.idl',
             'events/CustomEvent.idl',
             'events/ErrorEvent.idl',
             'events/Event.idl',
             'events/FocusEvent.idl',
             'events/HashChangeEvent.idl',
             'events/KeyboardEvent.idl',
             'events/MessageEvent.idl',
             'events/MouseEvent.idl',
             'events/MutationEvent.idl',
-            'events/OverflowEvent.idl',
             'events/PageTransitionEvent.idl',
             'events/PointerEvent.idl',
             'events/PopStateEvent.idl',
             'events/ProgressEvent.idl',
             'events/PromiseRejectionEvent.idl',
             'events/RelatedEvent.idl',
             'events/ResourceProgressEvent.idl',
             'events/SecurityPolicyViolationEvent.idl',
             'events/TextEvent.idl',
             'events/TouchEvent.idl',
@@ skipping 1997 matching lines @@
             'events/MessageEvent.cpp',
             'events/MessageEvent.h',
             'events/MouseEvent.cpp',
             'events/MouseRelatedEvent.cpp',
             'events/MutationEvent.cpp',
             'events/MutationEvent.h',
             'events/NavigatorEvents.cpp',
             'events/NavigatorEvents.h',
             'events/NodeEventContext.cpp',
             'events/NodeEventContext.h',
-            'events/OverflowEvent.cpp',
-            'events/OverflowEvent.h',
             'events/PageTransitionEvent.cpp',
             'events/PageTransitionEvent.h',
             'events/PointerEvent.cpp',
             'events/PointerEvent.h',
             'events/PointerIdManager.cpp',
             'events/PointerIdManager.h',
             'events/PopStateEvent.cpp',
             'events/PopStateEvent.h',
             'events/ProgressEvent.cpp',
             'events/ProgressEvent.h',
@@ skipping 939 matching lines @@
             'events/CompositionEventInit.idl',
             'events/CustomEventInit.idl',
             'events/ErrorEventInit.idl',
             'events/EventInit.idl',
             'events/EventModifierInit.idl',
             'events/FocusEventInit.idl',
             'events/HashChangeEventInit.idl',
             'events/KeyboardEventInit.idl',
             'events/MessageEventInit.idl',
             'events/MouseEventInit.idl',
-            'events/OverflowEventInit.idl',
             'events/PageTransitionEventInit.idl',
             'events/PointerEventInit.idl',
             'events/PopStateEventInit.idl',
             'events/ProgressEventInit.idl',
             'events/PromiseRejectionEventInit.idl',
             'events/RelatedEventInit.idl',
             'events/SecurityPolicyViolationEventInit.idl',
             'events/TransitionEventInit.idl',
             'events/UIEventInit.idl',
             'events/WheelEventInit.idl',
@@ skipping 48 matching lines @@
             '<(blink_core_output_dir)/events/FocusEventInit.cpp',
             '<(blink_core_output_dir)/events/FocusEventInit.h',
             '<(blink_core_output_dir)/events/HashChangeEventInit.cpp',
             '<(blink_core_output_dir)/events/HashChangeEventInit.h',
             '<(blink_core_output_dir)/events/KeyboardEventInit.cpp',
             '<(blink_core_output_dir)/events/KeyboardEventInit.h',
             '<(blink_core_output_dir)/events/MessageEventInit.cpp',
             '<(blink_core_output_dir)/events/MessageEventInit.h',
             '<(blink_core_output_dir)/events/MouseEventInit.cpp',
             '<(blink_core_output_dir)/events/MouseEventInit.h',
-            '<(blink_core_output_dir)/events/OverflowEventInit.cpp',
-            '<(blink_core_output_dir)/events/OverflowEventInit.h',
             '<(blink_core_output_dir)/events/PageTransitionEventInit.cpp',
             '<(blink_core_output_dir)/events/PageTransitionEventInit.h',
             '<(blink_core_output_dir)/events/PointerEventInit.cpp',
             '<(blink_core_output_dir)/events/PointerEventInit.h',
             '<(blink_core_output_dir)/events/PopStateEventInit.cpp',
             '<(blink_core_output_dir)/events/PopStateEventInit.h',
             '<(blink_core_output_dir)/events/ProgressEventInit.cpp',
             '<(blink_core_output_dir)/events/ProgressEventInit.h',
             '<(blink_core_output_dir)/events/PromiseRejectionEventInit.cpp',
             '<(blink_core_output_dir)/events/PromiseRejectionEventInit.h',
@@ skipping 258 matching lines @@
             'style/OutlineValueTest.cpp',
             'style/SVGComputedStyleTest.cpp',
             'svg/UnsafeSVGAttributeSanitizationTest.cpp',
             'testing/PrivateScriptTestTest.cpp',
             'timing/MemoryInfoTest.cpp',
             'workers/WorkerThreadTest.cpp',
             'xml/parser/SharedBufferReaderTest.cpp',
         ],
     }
 }