Remove CSS regions support, keeping a bare minimum to support "region-based" multicol.

Source/core/rendering/RenderMultiColumnSet.h

Index: Source/core/rendering/RenderMultiColumnSet.h
diff --git a/Source/core/rendering/RenderMultiColumnSet.h b/Source/core/rendering/RenderMultiColumnSet.h
index 4ece7e3b9f68adf3fe2944548ecc159dc4e3b440..0e0152f35b3356e3d42ccfd1fb16d0ae8e3850b4 100644
--- a/Source/core/rendering/RenderMultiColumnSet.h
+++ b/Source/core/rendering/RenderMultiColumnSet.h
@@ -97,10 +97,6 @@ private:
     // FIXME: This will change once we have column sets constrained by enclosing pages, etc.
     virtual LayoutUnit logicalHeightOfAllFlowThreadContent() const OVERRIDE { return m_computedColumnHeight; }
 
-    // FIXME: For now we return false, but it's likely we will leverage the auto height region code to do column
-    // balancing. That's why we have an override of this function that is distinct from RenderRegionSet's override.
-    virtual bool shouldHaveAutoLogicalHeight() const OVERRIDE { return false; }
-
     virtual void repaintFlowThreadContent(const LayoutRect& repaintRect) const OVERRIDE;
 
     virtual void collectLayerFragments(LayerFragments&, const LayoutRect& layerBoundingBox, const LayoutRect& dirtyRect) OVERRIDE;