[CSS Regions] Elements in a region should be assignable to a named flow

Source/core/rendering/RenderObject.h

Index: Source/core/rendering/RenderObject.h
diff --git a/Source/core/rendering/RenderObject.h b/Source/core/rendering/RenderObject.h
index 243ec1b567aab566c283fc4c20a29e04e365f1fd..0b83813aa3ab6c10ce11b0bb2ecc8a178f6d8663 100644
--- a/Source/core/rendering/RenderObject.h
+++ b/Source/core/rendering/RenderObject.h
@@ -249,6 +249,7 @@ public:
     // RenderObject tree manipulation
     //////////////////////////////////////////
     virtual bool canHaveChildren() const { return virtualChildren(); }
+    virtual bool canDOMChildrenHaveRenderParent() const { return false; } // Even if this render object can't have render children, the children in the DOM tree may have a render parent (that is different from this object).
     virtual bool canHaveGeneratedChildren() const;
     virtual bool isChildAllowed(RenderObject*, RenderStyle*) const { return true; }
     virtual void addChild(RenderObject* newChild, RenderObject* beforeChild = 0);