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

Source/core/rendering/RenderFlowThread.cpp

Index: Source/core/rendering/RenderFlowThread.cpp
diff --git a/Source/core/rendering/RenderFlowThread.cpp b/Source/core/rendering/RenderFlowThread.cpp
index 5412e8893ccfaa9d248fcfb6b0fc2423a32d2d57..d426d53b9395b16ad0d9a6ec9823cc3c0e0efee4 100644
--- a/Source/core/rendering/RenderFlowThread.cpp
+++ b/Source/core/rendering/RenderFlowThread.cpp
@@ -71,13 +71,6 @@ PassRefPtr<RenderStyle> RenderFlowThread::createFlowThreadStyle(RenderStyle* par
     return newStyle.release();
 }
 
-void RenderFlowThread::addRegionToThread(RenderRegion* renderRegion)
-{
-    ASSERT(renderRegion);
-    m_regionList.add(renderRegion);
-    renderRegion->setIsValid(true);
-}
-
 void RenderFlowThread::removeRegionFromThread(RenderRegion* renderRegion)
 {
     ASSERT(renderRegion);
@@ -212,13 +205,10 @@ void RenderFlowThread::repaintRectangleInRegions(const LayoutRect& repaintRect)
     }
 }
 
-RenderRegion* RenderFlowThread::regionAtBlockOffset(LayoutUnit offset, bool extendLastRegion, RegionAutoGenerationPolicy autoGenerationPolicy)
+RenderRegion* RenderFlowThread::regionAtBlockOffset(LayoutUnit offset)
 {
     ASSERT(!m_regionsInvalidated);
 
-    if (autoGenerationPolicy == AllowRegionAutoGeneration)
-        autoGenerateRegionsToBlockOffset(offset);
-
     if (offset <= 0)
         return m_regionList.isEmpty() ? 0 : m_regionList.first();
 
@@ -226,7 +216,6 @@ RenderRegion* RenderFlowThread::regionAtBlockOffset(LayoutUnit offset, bool exte
     m_regionIntervalTree.allOverlapsWithAdapter<RegionSearchAdapter>(adapter);
 
     // If no region was found, the offset is in the flow thread overflow.
-    // The last region will contain the offset if extendLastRegion is set or if the last region is a set.
     if (!adapter.result() && !m_regionList.isEmpty())
         return m_regionList.last();
 
@@ -318,7 +307,7 @@ LayoutUnit RenderFlowThread::pageLogicalTopForOffset(LayoutUnit offset)
 
 LayoutUnit RenderFlowThread::pageLogicalWidthForOffset(LayoutUnit offset)
 {
-    RenderRegion* region = regionAtBlockOffset(offset, true);
+    RenderRegion* region = regionAtBlockOffset(offset);
     return region ? region->pageLogicalWidth() : contentLogicalWidth();
 }
 
@@ -362,7 +351,7 @@ RenderRegion* RenderFlowThread::mapFromFlowToRegion(TransformState& transformSta
     // Note: Using the center in order to avoid rounding errors.
 
     LayoutPoint center = boxRect.center();
-    RenderRegion* renderRegion = const_cast<RenderFlowThread*>(this)->regionAtBlockOffset(isHorizontalWritingMode() ? center.y() : center.x(), true, DisallowRegionAutoGeneration);
+    RenderRegion* renderRegion = const_cast<RenderFlowThread*>(this)->regionAtBlockOffset(isHorizontalWritingMode() ? center.y() : center.x());
     if (!renderRegion)
         return 0;
 
@@ -394,8 +383,8 @@ void RenderFlowThread::setRegionRangeForBox(const RenderBox* box, LayoutUnit off
         return;
 
     // FIXME: Not right for differing writing-modes.
-    RenderRegion* startRegion = regionAtBlockOffset(offsetFromLogicalTopOfFirstPage, true);
-    RenderRegion* endRegion = regionAtBlockOffset(offsetFromLogicalTopOfFirstPage + box->logicalHeight(), true);
+    RenderRegion* startRegion = regionAtBlockOffset(offsetFromLogicalTopOfFirstPage);
+    RenderRegion* endRegion = regionAtBlockOffset(offsetFromLogicalTopOfFirstPage + box->logicalHeight());
     RenderRegionRangeMap::iterator it = m_regionRangeMap.find(box);
     if (it == m_regionRangeMap.end()) {
         m_regionRangeMap.set(box, RenderRegionRange(startRegion, endRegion));