[New Multicolumn] Preparatory work for nested multicol support.

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 258 matching lines @@
     if (!m_needsColumnHeightsRecalculation)
         return false;
 
     // Column heights may change here because of balancing. We may have to do multiple layout
     // passes, depending on how the contents is fitted to the changed column heights. In most
     // cases, laying out again twice or even just once will suffice. Sometimes we need more
     // passes than that, though, but the number of retries should not exceed the number of
     // columns, unless we have a bug.
     bool needsRelayout = false;
     for (RenderMultiColumnSet* multicolSet = firstMultiColumnSet(); multicolSet; multicolSet = multicolSet->nextSiblingMultiColumnSet()) {
-        needsRelayout |= multicolSet->recalculateColumnHeight(m_inBalancingPass ? RenderMultiColumnSet::StretchBySpaceShortage : RenderMultiColumnSet::GuessFromFlowThreadPortion);
+        needsRelayout |= multicolSet->recalculateColumnHeight(m_inBalancingPass ? StretchBySpaceShortage : GuessFromFlowThreadPortion);
         if (needsRelayout) {
             // Once a column set gets a new column height, that column set and all successive column
             // sets need to be laid out over again, since their logical top will be affected by
             // this, and therefore their column heights may change as well, at least if the multicol
             // height is constrained.
             multicolSet->setChildNeedsLayout(MarkOnlyThis);
         }
     }
 
     if (needsRelayout)
@@ skipping 350 matching lines @@
 void RenderMultiColumnFlowThread::setPageBreak(LayoutUnit offset, LayoutUnit spaceShortage)
 {
     // Only positive values are interesting (and allowed) here. Zero space shortage may be reported
     // when we're at the top of a column and the element has zero height. Ignore this, and also
     // ignore any negative values, which may occur when we set an early break in order to honor
     // widows in the next column.
     if (spaceShortage <= 0)
         return;
 
     if (RenderMultiColumnSet* multicolSet = columnSetAtBlockOffset(offset))
-        multicolSet->recordSpaceShortage(spaceShortage);
+        multicolSet->recordSpaceShortage(offset, spaceShortage);
 }
 
 void RenderMultiColumnFlowThread::updateMinimumPageHeight(LayoutUnit offset, LayoutUnit minHeight)
 {
     if (RenderMultiColumnSet* multicolSet = columnSetAtBlockOffset(offset))
-        multicolSet->updateMinimumColumnHeight(minHeight);
+        multicolSet->updateMinimumColumnHeight(offset, minHeight);
 }
 
 bool RenderMultiColumnFlowThread::addForcedRegionBreak(LayoutUnit offset, LayoutObject* /*breakChild*/, bool /*isBefore*/, LayoutUnit* offsetBreakAdjustment)
 {
     if (RenderMultiColumnSet* multicolSet = columnSetAtBlockOffset(offset)) {
         multicolSet->addContentRun(offset);
         if (offsetBreakAdjustment)
             *offsetBreakAdjustment = pageLogicalHeightForOffset(offset) ? pageRemainingLogicalHeightForOffset(offset, IncludePageBoundary) : LayoutUnit();
         return true;
     }
     return false;
 }
 
 bool RenderMultiColumnFlowThread::isPageLogicalHeightKnown() const
 {
     if (RenderMultiColumnSet* columnSet = lastMultiColumnSet())
         return columnSet->pageLogicalHeight();
     return false;
 }
 
 }