[New Multicolumn] Support for paged overflow. (By mstensho).

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 97758808da1264b65e6c1a4b3f3df2ccc2bfeb77..add6816561a6e3b3524f91faefe21b971c26b5f1 100644
--- a/Source/core/rendering/RenderFlowThread.h
+++ b/Source/core/rendering/RenderFlowThread.h
@@ -59,6 +59,7 @@ public:
 
     virtual bool isRenderFlowThread() const OVERRIDE FINAL { return true; }
     virtual bool isRenderMultiColumnFlowThread() const { return false; }
+    virtual bool isRenderPagedFlowThread() const { return false; }
 
     virtual void layout() OVERRIDE;