Add development Blink setting for impl-side rubber-banding

Source/core/frame/FrameView.cpp

Index: Source/core/frame/FrameView.cpp
diff --git a/Source/core/frame/FrameView.cpp b/Source/core/frame/FrameView.cpp
index 188618cdc1c779852a5b044e7e23fe886d8bbbdb..32e6afeb1f457e4143f0082964d68097fead9350 100644
--- a/Source/core/frame/FrameView.cpp
+++ b/Source/core/frame/FrameView.cpp
@@ -1673,6 +1673,11 @@ bool FrameView::isRubberBandInProgress() const
     return false;
 }
 
+bool FrameView::rubberBandingOnCompositorThread() const
+{
+    return m_frame->settings()->rubberBandingOnCompositorThread();
+}
+
 HostWindow* FrameView::hostWindow() const
 {
     Page* page = frame().page();