[New Multicolumn] Add support for column-span:all

Source/core/rendering/RenderObject.cpp

Index: Source/core/rendering/RenderObject.cpp
diff --git a/Source/core/rendering/RenderObject.cpp b/Source/core/rendering/RenderObject.cpp
index 0186feb8cbcd223be39405970e32c2e8f87baa64..2d79b40e3f59b0233e789b1d1fac1b8bc914f1c1 100644
--- a/Source/core/rendering/RenderObject.cpp
+++ b/Source/core/rendering/RenderObject.cpp
@@ -2735,6 +2735,9 @@ void RenderObject::insertedIntoTree()
 
     if (!isFloating() && parent()->childrenInline())
         parent()->dirtyLinesFromChangedChild(this);
+
+    if (RenderFlowThread* flowThread = parent()->flowThreadContainingBlock())
+        flowThread->flowThreadDescendantInserted(this);
 }
 
 void RenderObject::willBeRemovedFromTree()
@@ -2785,6 +2788,8 @@ void RenderObject::removeFromRenderFlowThreadRecursive(RenderFlowThread* renderF
             child->removeFromRenderFlowThreadRecursive(renderFlowThread);
     }
 
+    if (renderFlowThread)
+        renderFlowThread->flowThreadDescendantOrSiblingWillBeRemoved(this);
     setFlowThreadState(NotInsideFlowThread);
 }