[New Multicolumn] Add support for 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 863de779c03ec792c6e9a7508f1723fe6c4e6af6..f72a95f1017e0e44ed6a827c81918c2fd8916005 100644
--- a/Source/core/rendering/RenderObject.h
+++ b/Source/core/rendering/RenderObject.h
@@ -325,6 +325,9 @@ 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;
@@ -387,6 +390,7 @@ public:
     virtual bool isRenderImage() const { return false; }
     virtual bool isRenderInline() const { return false; }
     virtual bool isRenderMultiColumnSet() const { return false; }
+    virtual bool isRenderMultiColumnSpannerSet() const { return false; }
     virtual bool isRenderPart() const { return false; }
     virtual bool isRenderRegion() const { return false; }
     virtual bool isRenderScrollbarPart() const { return false; }
@@ -528,7 +532,7 @@ public:
         // RenderBlock::createAnonymousBlock(). This includes creating an anonymous
         // RenderBlock having a BLOCK or BOX display. Other classes such as RenderTextFragment
         // are not RenderBlocks and will return false. See https://bugs.webkit.org/show_bug.cgi?id=56709.
-        return isAnonymous() && (style()->display() == BLOCK || style()->display() == BOX) && style()->styleType() == NOPSEUDO && isRenderBlock() && !isListMarker() && !isRenderFlowThread()
+        return isAnonymous() && (style()->display() == BLOCK || style()->display() == BOX) && style()->styleType() == NOPSEUDO && isRenderBlock() && !isListMarker() && !isRenderFlowThread() && !isRenderMultiColumnSet()
             && !isRenderFullScreen()
             && !isRenderFullScreenPlaceholder();
     }
@@ -650,6 +654,8 @@ 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.