[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 85c01c124a1339d0a975bdf92df359374f37d939..754c926e0206b35e9b50f72941ea8a40fc1b4bf7 100644
--- a/Source/core/rendering/RenderObject.h
+++ b/Source/core/rendering/RenderObject.h
@@ -301,6 +301,9 @@ 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;
@@ -358,6 +361,7 @@ public:
     bool isRenderIFrame() const { return isOfType(RenderObjectRenderIFrame); }
     bool isRenderImage() const { return isOfType(RenderObjectRenderImage); }
     bool isRenderMultiColumnSet() const { return isOfType(RenderObjectRenderMultiColumnSet); }
+    bool isRenderMultiColumnSpannerSet() const { return isOfType(RenderObjectRenderMultiColumnSpannerSet); }
     bool isRenderRegion() const { return isOfType(RenderObjectRenderRegion); }
     bool isRenderScrollbarPart() const { return isOfType(RenderObjectRenderScrollbarPart); }
     bool isRenderTableCol() const { return isOfType(RenderObjectRenderTableCol); }
@@ -508,7 +512,7 @@ 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();
     }
@@ -630,6 +634,8 @@ 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.
@@ -1080,6 +1086,7 @@ protected:
         RenderObjectRenderImage,
         RenderObjectRenderInline,
         RenderObjectRenderMultiColumnSet,
+        RenderObjectRenderMultiColumnSpannerSet,
         RenderObjectRenderPart,
         RenderObjectRenderRegion,
         RenderObjectRenderScrollbarPart,