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

Source/core/rendering/RenderView.h

Index: Source/core/rendering/RenderView.h
diff --git a/Source/core/rendering/RenderView.h b/Source/core/rendering/RenderView.h
index 8806bfda696df8e3370bb51da67285b9ab727cd4..8d1f8b4ddaf1a615017219a1135d67d29698f385 100644
--- a/Source/core/rendering/RenderView.h
+++ b/Source/core/rendering/RenderView.h
@@ -174,12 +174,8 @@ public:
     // Renderer that paints the root background has background-images which all have background-attachment: fixed.
     bool rootBackgroundIsEntirelyFixed() const;
 
-    bool hasRenderNamedFlowThreads() const;
-    bool checkTwoPassLayoutForAutoHeightRegions() const;
     FlowThreadController* flowThreadController();
 
-    virtual void styleDidChange(StyleDifference, const RenderStyle* oldStyle) OVERRIDE;
-
     IntervalArena* intervalArena();
 
     void setRenderQuoteHead(RenderQuote* head) { m_renderQuoteHead = head; }
@@ -242,7 +238,6 @@ private:
     void enableLayoutState() { ASSERT(m_layoutStateDisableCount > 0); m_layoutStateDisableCount--; }
 
     void layoutContent(const LayoutState&);
-    void layoutContentInAutoLogicalHeightRegions(const LayoutState&);
 #ifndef NDEBUG
     void checkLayoutState(const LayoutState&);
 #endif