Merge 125351

Source/WebCore/rendering/RenderBoxModelObject.cpp

Index: Source/WebCore/rendering/RenderBoxModelObject.cpp
===================================================================
--- Source/WebCore/rendering/RenderBoxModelObject.cpp	(revision 126659)
+++ Source/WebCore/rendering/RenderBoxModelObject.cpp	(working copy)
@@ -2749,9 +2749,8 @@
 
 void RenderBoxModelObject::moveChildTo(RenderBoxModelObject* toBoxModelObject, RenderObject* child, RenderObject* beforeChild, bool fullRemoveInsert)
 {
-    // FIXME: We need a performant way to handle clearing positioned objects from our list that are
-    // in |child|'s subtree so we could just clear them here. Because of this, we assume that callers
-    // have cleared their positioned objects list for child moves (!fullRemoveInsert) to avoid any badness.
+    // We assume that callers have cleared their positioned objects list for child moves (!fullRemoveInsert) so the
+    // positioned renderer maps don't become stale. It would be too slow to do the map lookup on each call.
     ASSERT(!fullRemoveInsert || !isRenderBlock() || !toRenderBlock(this)->hasPositionedObjects());
 
     ASSERT(this == child->parent());