[New Multicolumn] Use the return value from flipForWritingMode().

Source/core/rendering/RenderMultiColumnFlowThread.cpp

 /*
  * Copyright (C) 2012 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:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 110 matching lines @@
     deleteLineBoxTree();
 
     destroy();
 }
 
 LayoutSize RenderMultiColumnFlowThread::columnOffset(const LayoutPoint& point) const
 {
     if (!hasValidRegionInfo())
         return LayoutSize(0, 0);
 
-    LayoutPoint flowThreadPoint(point);
-    flipForWritingMode(flowThreadPoint);
+    LayoutPoint flowThreadPoint = flipForWritingMode(point);
     LayoutUnit blockOffset = isHorizontalWritingMode() ? flowThreadPoint.y() : flowThreadPoint.x();
     RenderMultiColumnSet* columnSet = columnSetAtBlockOffset(blockOffset);
     if (!columnSet)
         return LayoutSize(0, 0);
     return columnSet->flowThreadTranslationAtOffset(blockOffset);
 }
 
 bool RenderMultiColumnFlowThread::needsNewWidth() const
 {
     LayoutUnit newWidth;
@@ skipping 171 matching lines @@
 }
 
 bool RenderMultiColumnFlowThread::isPageLogicalHeightKnown() const
 {
     if (RenderMultiColumnSet* columnSet = lastMultiColumnSet())
         return columnSet->pageLogicalHeight();
     return false;
 }
 
 }