Add development Blink setting for impl-side rubber-banding

Source/core/frame/FrameView.h

 /*
    Copyright (C) 1997 Martin Jones (mjones@kde.org)
              (C) 1998 Waldo Bastian (bastian@kde.org)
              (C) 1998, 1999 Torben Weis (weis@kde.org)
              (C) 1999 Lars Knoll (knoll@kde.org)
              (C) 1999 Antti Koivisto (koivisto@kde.org)
    Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009 Apple Inc. All rights reserved.
 
    This library is free software; you can redistribute it and/or
    modify it under the terms of the GNU Library General Public
@@ skipping 145 matching lines @@
     void setVisibleContentScaleFactor(float);
 
     // Scale used to convert incoming input events. Usually the same as visibleContentScaleFactor(), unless specifically changed.
     float inputEventsScaleFactor() const;
     // Offset used to convert incoming input events while emulating device metics.
     IntSize inputEventsOffsetForEmulation() const;
     void setInputEventsTransformForEmulation(const IntSize&, float);
 
     void setScrollPosition(const DoublePoint&, ScrollBehavior = ScrollBehaviorInstant);
     virtual bool isRubberBandInProgress() const override;
+    virtual bool rubberBandingOnCompositorThread() const override;
     void setScrollPositionNonProgrammatically(const IntPoint&);
 
     // This is different than visibleContentRect() in that it ignores negative (or overly positive)
     // offsets from rubber-banding, and it takes zooming into account.
     LayoutRect viewportConstrainedVisibleContentRect() const;
     void viewportConstrainedVisibleContentSizeChanged(bool widthChanged, bool heightChanged);
 
     AtomicString mediaType() const;
     void setMediaType(const AtomicString&);
     void adjustMediaTypeForPrinting(bool printing);
@@ skipping 661 matching lines @@
     }
 
 private:
     RawPtrWillBeMember<FrameView> m_view;
     bool m_originalValue;
 };
 
 } // namespace blink
 
 #endif // FrameView_h