[New Multicolumn] Actual support for layout of column-span:all.

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 6fbfd292742396ac3e6073297d0653faec32dcf7..500698bbda4a99ec50467e8d645b3c0841d8a3a0 100644
--- a/Source/core/rendering/RenderObject.h
+++ b/Source/core/rendering/RenderObject.h
@@ -300,6 +300,9 @@ private:
     void addAbsoluteRectForLayer(LayoutRect& result);
     bool requiresAnonymousTableWrappers(const RenderObject*) const;
 
+    // This renderer has column-span:all, but is it really a valid column spanner?
+    bool isValidColumnSpanAll() const;
+
     // Gets pseudoStyle from Shadow host(in case of input elements)
     // or from Parent element.
     PassRefPtr<RenderStyle> getUncachedPseudoStyleFromParentOrShadowHost() const;
@@ -386,6 +389,7 @@ public:
     virtual bool isRenderBlock() const { return false; }
     virtual bool isRenderBlockFlow() const { return false; }
     virtual bool isRenderFlowThread() const { return false; }
+    virtual bool isRenderMultiColumnFlowThread() const { return false; }
     virtual bool isRenderInline() const { return false; }
     virtual bool isRenderPart() const { return false; }
 
@@ -634,11 +638,15 @@ public:
     Document& document() const { return m_node->document(); }
     LocalFrame* frame() const { return document().frame(); }
 
+    bool isColumnSpanAll() const { return style()->columnSpan() == ColumnSpanAll && isValidColumnSpanAll(); }
+
     // Returns the object containing this one. Can be different from parent for positioned elements.
     // If paintInvalidationContainer and paintInvalidationContainerSkipped are not null, on return *paintInvalidationContainerSkipped
     // is true if the renderer returned is an ancestor of paintInvalidationContainer.
     RenderObject* container(const RenderLayerModelObject* paintInvalidationContainer = 0, bool* paintInvalidationContainerSkipped = 0) const;
     RenderBlock* containerForFixedPosition(const RenderLayerModelObject* paintInvalidationContainer = 0, bool* paintInvalidationContainerSkipped = 0) const;
+    RenderBlock* containerForAbsolutePosition() const;
+    RenderBlock* parentBlock() const;
 
     virtual RenderObject* hoverAncestor() const { return parent(); }