[New Multicolumn] Make fast/multicol/overflow-content.html pass in the new implementation.

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 805f1fa47dc66525eb355537977af6504e13b17a..4bd563580d6303d4252cf3feb807fdc4861d9202 100644
--- a/Source/core/rendering/RenderFlowThread.cpp
+++ b/Source/core/rendering/RenderFlowThread.cpp
@@ -362,13 +362,6 @@ void RenderFlowThread::getRegionRangeForBox(const RenderBox* box, RenderRegion*&
     ASSERT(m_regionList.contains(startRegion) && m_regionList.contains(endRegion));
 }
 
-void RenderFlowThread::applyBreakAfterContent(LayoutUnit clientHeight)
-{
-    // Simulate a region break at height. If it points inside an auto logical height region,
-    // then it may determine the region computed autoheight.
-    addForcedRegionBreak(clientHeight, this, false);
-}
-
 void RenderFlowThread::updateRegionsFlowThreadPortionRect()
 {
     LayoutUnit logicalHeight = 0;