Remove unused methods and variables in RenderFlowThread.

Source/core/rendering/RenderFlowThread.h

Index: Source/core/rendering/RenderFlowThread.h
diff --git a/Source/core/rendering/RenderFlowThread.h b/Source/core/rendering/RenderFlowThread.h
index deaa5e336fe963caa2cd03ff9d7c9f47076e2267..c0d7b3b1021d3b3e8c87da915cd9f1c9d765034a 100644
--- a/Source/core/rendering/RenderFlowThread.h
+++ b/Source/core/rendering/RenderFlowThread.h
@@ -80,14 +80,11 @@ public:
     void invalidateRegions();
     bool hasValidRegionInfo() const { return !m_regionsInvalidated && !m_regionList.isEmpty(); }
 
-    static PassRefPtr<RenderStyle> createFlowThreadStyle(RenderStyle* parentStyle);
-
     void repaintRectangleInRegions(const LayoutRect&) const;
 
     LayoutPoint adjustedPositionRelativeToOffsetParent(const RenderBoxModelObject&, const LayoutPoint&);
 
     LayoutUnit pageLogicalTopForOffset(LayoutUnit);
-    LayoutUnit pageLogicalWidthForOffset(LayoutUnit);
     LayoutUnit pageLogicalHeightForOffset(LayoutUnit);
     LayoutUnit pageRemainingLogicalHeightForOffset(LayoutUnit, PageBoundaryRule = IncludePageBoundary);
 
@@ -107,9 +104,6 @@ public:
     RenderRegion* firstRegion() const;
     RenderRegion* lastRegion() const;
 
-    bool previousRegionCountChanged() const { return m_previousRegionCount != m_regionList.size(); }
-    void updatePreviousRegionCount() { m_previousRegionCount = m_regionList.size(); }
-
     void setRegionRangeForBox(const RenderBox*, LayoutUnit offsetFromLogicalTopOfFirstPage);
     void getRegionRangeForBox(const RenderBox*, RenderRegion*& startRegion, RenderRegion*& endRegion) const;
 
@@ -150,7 +144,6 @@ protected:
     const RenderBox* currentStatePusherRenderBox() const;
 
     RenderRegionList m_regionList;
-    unsigned short m_previousRegionCount;
 
     class RenderRegionRange {
     public: