Merge 122861 - Incorrect offset used for scrollWidth/Height calculation

Source/WebCore/rendering/RenderLayer.cpp

Index: Source/WebCore/rendering/RenderLayer.cpp
===================================================================
--- Source/WebCore/rendering/RenderLayer.cpp	(revision 123231)
+++ Source/WebCore/rendering/RenderLayer.cpp	(working copy)
@@ -1580,8 +1580,8 @@
         if (!box)
             return;
 
-        int maxX = scrollWidth() - box->clientWidth();
-        int maxY = scrollHeight() - box->clientHeight();
+        int maxX = scrollWidth() - box->pixelSnappedClientWidth();
+        int maxY = scrollHeight() - box->pixelSnappedClientHeight();
 
         x = min(max(x, 0), maxX);
         y = min(max(y, 0), maxY);
@@ -2409,7 +2409,7 @@
     ASSERT(renderBox());
     if (m_scrollDimensionsDirty)
         const_cast<RenderLayer*>(this)->computeScrollDimensions();
-    return snapSizeToPixel(m_scrollSize.width(), renderBox()->clientLeft());
+    return snapSizeToPixel(m_scrollSize.width(), renderBox()->clientLeft() + renderBox()->x());
 }
 
 int RenderLayer::scrollHeight() const
@@ -2417,7 +2417,7 @@
     ASSERT(renderBox());
     if (m_scrollDimensionsDirty)
         const_cast<RenderLayer*>(this)->computeScrollDimensions();
-    return snapSizeToPixel(m_scrollSize.height(), renderBox()->clientTop());
+    return snapSizeToPixel(m_scrollSize.height(), renderBox()->clientTop() + renderBox()->y());
 }
 
 LayoutUnit RenderLayer::overflowTop() const