Prepare height calculation methods in LayoutFlowThread for nested multicol.

Source/core/layout/LayoutPagedFlowThread.cpp

Index: Source/core/layout/LayoutPagedFlowThread.cpp
diff --git a/Source/core/layout/LayoutPagedFlowThread.cpp b/Source/core/layout/LayoutPagedFlowThread.cpp
index 43105d001bc2e2daa969ca01a0d9fa6d4922b733..895f7ef044e529d96d7442e0ae4f89d57600cfe3 100644
--- a/Source/core/layout/LayoutPagedFlowThread.cpp
+++ b/Source/core/layout/LayoutPagedFlowThread.cpp
@@ -46,7 +46,7 @@ void LayoutPagedFlowThread::layout()
     LayoutMultiColumnSet* columnSet = firstMultiColumnSet();
     if (!columnSet)
         return;
-    LayoutUnit pageLogicalHeight = columnSet->pageLogicalHeight();
+    LayoutUnit pageLogicalHeight = columnSet->pageLogicalHeightForOffset(LayoutUnit());
     if (!pageLogicalHeight)
         return; // Page height not calculated yet. Happens in the first layout pass when height is auto.
     // Ensure uniform page height. We don't want the last page to be shorter than the others,