[New Multicolumn] Create RenderMultiColumnSet during renderer creation, not during layout.

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 27 matching lines @@
     : RenderRegionSet(0, flowThread)
     , m_computedColumnCount(1)
     , m_computedColumnWidth(0)
     , m_computedColumnHeight(0)
     , m_maxColumnHeight(RenderFlowThread::maxLogicalHeight())
     , m_minSpaceShortage(RenderFlowThread::maxLogicalHeight())
     , m_minimumColumnHeight(0)
 {
 }
 
-RenderMultiColumnSet* RenderMultiColumnSet::createAnonymous(RenderFlowThread* flowThread)
+RenderMultiColumnSet* RenderMultiColumnSet::createAnonymous(RenderFlowThread* flowThread, RenderStyle* parentStyle)
 {
     Document& document = flowThread->document();
     RenderMultiColumnSet* renderer = new RenderMultiColumnSet(flowThread);
     renderer->setDocumentForAnonymous(&document);
+    renderer->setStyle(RenderStyle::createAnonymousStyleWithDisplay(parentStyle, BLOCK));
     return renderer;
 }
 
+RenderMultiColumnSet* RenderMultiColumnSet::nextSiblingMultiColumnSet() const
+{
+    for (RenderObject* sibling = nextSibling(); sibling; sibling = sibling->nextSibling()) {
+        if (sibling->isRenderMultiColumnSet())
+            return toRenderMultiColumnSet(sibling);
+    }
+    return 0;
+}
+
 LayoutUnit RenderMultiColumnSet::heightAdjustedForSetOffset(LayoutUnit height) const
 {
     RenderBlockFlow* multicolBlock = multiColumnBlockFlow();
     LayoutUnit contentLogicalTop = logicalTop() - multicolBlock->borderBefore() - multicolBlock->paddingBefore();
 
     height -= contentLogicalTop;
     return max(height, LayoutUnit(1)); // Let's avoid zero height, as that would probably cause an infinite amount of columns to be created.
 }
 
 LayoutUnit RenderMultiColumnSet::pageLogicalTopForOffset(LayoutUnit offset) const
@@ skipping 518 matching lines @@
         fragments.append(fragment);
     }
 }
 
 const char* RenderMultiColumnSet::renderName() const
 {
     return "RenderMultiColumnSet";
 }
 
 }