Selectively disable rubber banding on mac.

Source/platform/scroll/ScrollableArea.cpp

 /*
  * Copyright (c) 2010, Google Inc. All rights reserved.
  * Copyright (C) 2008, 2011 Apple Inc. All Rights Reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
@@ skipping 190 matching lines @@
     else if (behaviorString == "smooth")
         behavior = ScrollBehaviorSmooth;
     else
         return false;
 
     return true;
 }
 
 bool ScrollableArea::handleWheelEvent(const PlatformWheelEvent& wheelEvent)
 {
-    return scrollAnimator()->handleWheelEvent(wheelEvent);
+    return handleWheelEvent(wheelEvent, true, true);
+}
+
+bool ScrollableArea::handleWheelEvent(const PlatformWheelEvent& wheelEvent, bool canRubberbandLeft, bool canRubberbandRight)
+{
+    return scrollAnimator()->handleWheelEvent(wheelEvent, canRubberbandLeft, canRubberbandRight);
 }
 
 // NOTE: Only called from Internals for testing.
 void ScrollableArea::setScrollOffsetFromInternals(const IntPoint& offset)
 {
     setScrollOffsetFromAnimation(offset);
 }
 
 void ScrollableArea::setScrollOffsetFromAnimation(const IntPoint& offset)
 {
@@ skipping 199 matching lines @@
 {
     return scrollSize(orientation);
 }
 
 float ScrollableArea::pixelStep(ScrollbarOrientation) const
 {
     return 1;
 }
 
 } // namespace WebCore