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

Source/core/rendering/RenderFlowThread.h

 /*
  * Copyright (C) 2011 Adobe Systems Incorporated. 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.
@@ skipping 49 matching lines @@
     virtual bool isRenderFlowThread() const OVERRIDE FINAL { return true; }
 
     virtual void layout() OVERRIDE FINAL;
 
     // Always create a RenderLayer for the RenderFlowThread so that we
     // can easily avoid drawing the children directly.
     virtual LayerType layerTypeRequired() const OVERRIDE FINAL { return NormalLayer; }
 
     virtual bool nodeAtPoint(const HitTestRequest&, HitTestResult&, const HitTestLocation& locationInContainer, const LayoutPoint& accumulatedOffset, HitTestAction) OVERRIDE FINAL;
 
-    virtual void addRegionToThread(RenderRegion*);
+    virtual void addRegionToThread(RenderRegion*) = 0;
     virtual void removeRegionFromThread(RenderRegion*);
     const RenderRegionList& renderRegionList() const { return m_regionList; }
 
     virtual void updateLogicalWidth() OVERRIDE FINAL;
     virtual void computeLogicalHeight(LayoutUnit logicalHeight, LayoutUnit logicalTop, LogicalExtentComputedValues&) const OVERRIDE;
 
     bool hasRegions() const { return m_regionList.size(); }
 
     void validateRegions();
     void invalidateRegions();
     bool hasValidRegionInfo() const { return !m_regionsInvalidated && !m_regionList.isEmpty(); }
 
     void repaintRectangleInRegions(const LayoutRect&) const;
 
     LayoutPoint adjustedPositionRelativeToOffsetParent(const RenderBoxModelObject&, const LayoutPoint&);
 
     LayoutUnit pageLogicalTopForOffset(LayoutUnit);
     LayoutUnit pageLogicalHeightForOffset(LayoutUnit);
     LayoutUnit pageRemainingLogicalHeightForOffset(LayoutUnit, PageBoundaryRule = IncludePageBoundary);
 
     virtual void setPageBreak(LayoutUnit /*offset*/, LayoutUnit /*spaceShortage*/) { }
     virtual void updateMinimumPageHeight(LayoutUnit /*offset*/, LayoutUnit /*minHeight*/) { }
 
-    enum RegionAutoGenerationPolicy {
-        AllowRegionAutoGeneration,
-        DisallowRegionAutoGeneration,
-    };
-    RenderRegion* regionAtBlockOffset(LayoutUnit, bool extendLastRegion = false, RegionAutoGenerationPolicy = AllowRegionAutoGeneration);
+    virtual RenderRegion* regionAtBlockOffset(LayoutUnit) const;
 
     bool regionsHaveUniformLogicalHeight() const { return m_regionsHaveUniformLogicalHeight; }
 
     RenderRegion* mapFromFlowToRegion(TransformState&) const;
 
     RenderRegion* firstRegion() const;
     RenderRegion* lastRegion() const;
 
     void setRegionRangeForBox(const RenderBox*, LayoutUnit offsetFromLogicalTopOfFirstPage);
     void getRegionRangeForBox(const RenderBox*, RenderRegion*& startRegion, RenderRegion*& endRegion) const;
@@ skipping 19 matching lines @@
 
     // Overridden by columns/pages to set up an initial logical width of the page width even when
     // no regions have been generated yet.
     virtual LayoutUnit initialLogicalWidth() const { return 0; };
 
     virtual void mapLocalToContainer(const RenderLayerModelObject* repaintContainer, TransformState&, MapCoordinatesFlags = ApplyContainerFlip, bool* wasFixed = 0) const OVERRIDE FINAL;
 
     void updateRegionsFlowThreadPortionRect();
     bool shouldRepaint(const LayoutRect&) const;
 
-    virtual void autoGenerateRegionsToBlockOffset(LayoutUnit) { }
-
     bool cachedOffsetFromLogicalTopOfFirstRegion(const RenderBox*, LayoutUnit&) const;
     void setOffsetFromLogicalTopOfFirstRegion(const RenderBox*, LayoutUnit);
     void clearOffsetFromLogicalTopOfFirstRegion(const RenderBox*);
 
     const RenderBox* currentStatePusherRenderBox() const;
 
     RenderRegionList m_regionList;
 
     class RenderRegionRange {
     public:
@@ skipping 80 matching lines @@
 };
 
 template <> struct ValueToString<RenderRegion*> {
     static String string(const RenderRegion* value) { return String::format("%p", value); }
 };
 #endif
 
 } // namespace WebCore
 
 #endif // RenderFlowThread_h