Prepare height calculation methods in LayoutFlowThread for nested multicol.

Source/core/layout/LayoutFlowThread.cpp

 /*
  * 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 98 matching lines @@
 {
     if (hitTestAction == HitTestBlockBackground)
         return false;
     return LayoutBlockFlow::nodeAtPoint(result, locationInContainer, accumulatedOffset, hitTestAction);
 }
 
 LayoutUnit LayoutFlowThread::pageLogicalHeightForOffset(LayoutUnit offset)
 {
     LayoutMultiColumnSet* columnSet = columnSetAtBlockOffset(offset);
     if (!columnSet)
-        return 0;
+        return LayoutUnit();
 
-    return columnSet->pageLogicalHeight();
+    return columnSet->pageLogicalHeightForOffset(offset);
 }
 
 LayoutUnit LayoutFlowThread::pageRemainingLogicalHeightForOffset(LayoutUnit offset, PageBoundaryRule pageBoundaryRule)
 {
     LayoutMultiColumnSet* columnSet = columnSetAtBlockOffset(offset);
     if (!columnSet)
-        return 0;
+        return LayoutUnit();
 
-    LayoutUnit pageLogicalTop = columnSet->pageLogicalTopForOffset(offset);
-    LayoutUnit pageLogicalHeight = columnSet->pageLogicalHeight();
-    LayoutUnit pageLogicalBottom = pageLogicalTop + pageLogicalHeight;
-    LayoutUnit remainingHeight = pageLogicalBottom - offset;
-    if (pageBoundaryRule == IncludePageBoundary) {
-        // If IncludePageBoundary is set, the line exactly on the top edge of a
-        // columnSet will act as being part of the previous columnSet.
-        remainingHeight = intMod(remainingHeight, pageLogicalHeight);
-    }
-    return remainingHeight;
+    return columnSet->pageRemainingLogicalHeightForOffset(offset, pageBoundaryRule);
 }
 
 void LayoutFlowThread::generateColumnSetIntervalTree()
 {
     // FIXME: Optimize not to clear the interval all the time. This implies manually managing the tree nodes lifecycle.
     m_multiColumnSetIntervalTree.clear();
     m_multiColumnSetIntervalTree.initIfNeeded();
     for (auto columnSet : m_multiColumnSetList)
         m_multiColumnSetIntervalTree.add(MultiColumnSetIntervalTree::createInterval(columnSet->logicalTopInFlowThread(), columnSet->logicalBottomInFlowThread(), columnSet));
 }
@@ skipping 32 matching lines @@
 
 void LayoutFlowThread::MultiColumnSetSearchAdapter::collectIfNeeded(const MultiColumnSetInterval& interval)
 {
     if (m_result)
         return;
     if (interval.low() <= m_offset && interval.high() > m_offset)
         m_result = interval.data();
 }
 
 } // namespace blink