Add rails to input wheel events.

Source/platform/scroll/ScrollAnimator.cpp

 /*
  * Copyright (c) 2010, Google 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.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 56 matching lines @@
 
 void ScrollAnimator::scrollToOffsetWithoutAnimation(const FloatPoint& offset)
 {
     m_currentPosX = offset.x();
     m_currentPosY = offset.y();
     notifyPositionChanged();
 }
 
 ScrollResult ScrollAnimator::handleWheelEvent(const PlatformWheelEvent& e)
 {
-    bool canScrollX = m_scrollableArea->userInputScrollable(HorizontalScrollbar);
-    bool canScrollY = m_scrollableArea->userInputScrollable(VerticalScrollbar);
+    bool canScrollX = m_scrollableArea->userInputScrollable(HorizontalScrollbar)
+        && e.railsMode() != PlatformEvent::RailsModeVertical;
+    bool canScrollY = m_scrollableArea->userInputScrollable(VerticalScrollbar)
+        && e.railsMode() != PlatformEvent::RailsModeHorizontal;
 
     // Accept the event if we are scrollable in that direction and can still
     // scroll any further.
     float deltaX = canScrollX ? e.deltaX() : 0;
     float deltaY = canScrollY ? e.deltaY() : 0;
 
     ScrollResult result(false);
 
 #if !OS(MACOSX)
     ScrollGranularity granularity = e.hasPreciseScrollingDeltas() ? ScrollByPrecisePixel : ScrollByPixel;
@@ skipping 71 matching lines @@
 }
 
 float ScrollAnimator::clampScrollPosition(ScrollbarOrientation orientation, float pos)
 {
     float maxScrollPos = m_scrollableArea->maximumScrollPosition(orientation);
     float minScrollPos = m_scrollableArea->minimumScrollPosition(orientation);
     return std::max(std::min(pos, maxScrollPos), minScrollPos);
 }
 
 } // namespace blink