Unifies ScrollView and RenderLayer to use non-shifted [minPos, maxPos] scroll offset

Source/core/platform/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 37 matching lines @@
 {
 }
 
 ScrollAnimator::~ScrollAnimator()
 {
 }
 
 bool ScrollAnimator::scroll(ScrollbarOrientation orientation, ScrollGranularity, float step, float multiplier)
 {
     float* currentPos = (orientation == HorizontalScrollbar) ? &m_currentPosX : &m_currentPosY;
-    float newPos = std::max(std::min(*currentPos + (step * multiplier), static_cast<float>(m_scrollableArea->scrollSize(orientation))), 0.0f);
+    float newPos = m_scrollableArea->clampScrollPosition(orientation, *currentPos + step * multiplier);
     float delta = *currentPos - newPos;
     if (*currentPos == newPos)
         return false;
     *currentPos = newPos;
 
     notifyPositionChanged(orientation == HorizontalScrollbar ? FloatSize(delta, 0) : FloatSize(0, delta));
 
     return true;
 }
 
@@ skipping 65 matching lines @@
     return FloatPoint(m_currentPosX, m_currentPosY);
 }
 
 void ScrollAnimator::notifyPositionChanged(const FloatSize& delta)
 {
     UNUSED_PARAM(delta);
     m_scrollableArea->setScrollOffsetFromAnimation(IntPoint(m_currentPosX, m_currentPosY));
 }
 
 } // namespace WebCore