[New Multicolumn] Faster and more direct RenderMultiColumnSet::multiColumnFlowThread().

Source/core/rendering/RenderMultiColumnSet.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 233 matching lines @@
     RenderBlockFlow* multicolBlock = multiColumnBlockFlow();
     RenderStyle* multicolStyle = multicolBlock->style();
 
     // Set box logical top.
     ASSERT(!previousSiblingBox() || !previousSiblingBox()->isRenderMultiColumnSet()); // FIXME: multiple set not implemented; need to examine previous set to calculate the correct logical top.
     setLogicalTop(multicolBlock->borderBefore() + multicolBlock->paddingBefore());
 
     // Set box width.
     updateLogicalWidth();
 
-    if (multicolBlock->multiColumnFlowThread()->requiresBalancing()) {
+    if (multiColumnFlowThread()->requiresBalancing()) {
         // Set maximum column height. We will not stretch beyond this.
         m_maxColumnHeight = RenderFlowThread::maxLogicalHeight();
         if (!multicolStyle->logicalHeight().isAuto()) {
             m_maxColumnHeight = multicolBlock->computeContentLogicalHeight(multicolStyle->logicalHeight(), -1);
             if (m_maxColumnHeight == -1)
                 m_maxColumnHeight = RenderFlowThread::maxLogicalHeight();
         }
         if (!multicolStyle->logicalMaxHeight().isUndefined()) {
             LayoutUnit logicalMaxHeight = multicolBlock->computeContentLogicalHeight(multicolStyle->logicalMaxHeight(), -1);
             if (logicalMaxHeight != -1 && m_maxColumnHeight > logicalMaxHeight)
                 m_maxColumnHeight = logicalMaxHeight;
         }
         m_maxColumnHeight = heightAdjustedForSetOffset(m_maxColumnHeight);
         m_computedColumnHeight = 0; // Restart balancing.
     } else {
-        setAndConstrainColumnHeight(heightAdjustedForSetOffset(multicolBlock->multiColumnFlowThread()->columnHeightAvailable()));
+        setAndConstrainColumnHeight(heightAdjustedForSetOffset(multiColumnFlowThread()->columnHeightAvailable()));
     }
 
     clearForcedBreaks();
 
     // Nuke previously stored minimum column height. Contents may have changed for all we know.
     m_minimumColumnHeight = 0;
 }
 
 void RenderMultiColumnSet::computeLogicalHeight(LayoutUnit, LayoutUnit logicalTop, LogicalExtentComputedValues& computedValues) const
 {
@@ skipping 313 matching lines @@
         fragments.append(fragment);
     }
 }
 
 const char* RenderMultiColumnSet::renderName() const
 {
     return "RenderMultiColumnSet";
 }
 
 }