Respect the smooth scrolling setting in LayerScrollableArea.

Source/core/layout/LayerScrollableArea.cpp

 /*
  * Copyright (C) 2006, 2007, 2008, 2009, 2010, 2011, 2012 Apple Inc. All rights reserved.
  *
  * Portions are Copyright (C) 1998 Netscape Communications Corporation.
  *
  * Other contributors:
  *   Robert O'Callahan <roc+@cs.cmu.edu>
  *   David Baron <dbaron@fas.harvard.edu>
  *   Christian Biesinger <cbiesinger@web.de>
  *   Randall Jesup <rjesup@wgate.com>
@@ skipping 470 matching lines @@
 IntSize LayerScrollableArea::overhangAmount() const
 {
     return IntSize();
 }
 
 IntPoint LayerScrollableArea::lastKnownMousePosition() const
 {
     return box().frame() ? box().frame()->eventHandler().lastKnownMousePosition() : IntPoint();
 }
 
+bool LayerScrollableArea::scrollAnimatorEnabled() const
+{
+    if (Settings* settings = box().frame()->settings())
+        return settings->scrollAnimatorEnabled();
+    return false;
+}
+
 bool LayerScrollableArea::shouldSuspendScrollAnimations() const
 {
     RenderView* view = box().view();
     if (!view)
         return true;
     return view->frameView()->shouldSuspendScrollAnimations();
 }
 
 bool LayerScrollableArea::scrollbarsCanBeActive() const
 {
@@ skipping 874 matching lines @@
 void LayerScrollableArea::setTopmostScrollChild(Layer* scrollChild)
 {
     // We only want to track the topmost scroll child for scrollable areas with
     // overlay scrollbars.
     if (!hasOverlayScrollbars())
         return;
     m_nextTopmostScrollChild = scrollChild;
 }
 
 } // namespace blink