Allow setNeedsLayout on positioned objects when no parent container

Source/core/layout/LayoutObject.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2000 Dirk Mueller (mueller@kde.org)
  *           (C) 2004 Allan Sandfeld Jensen (kde@carewolf.com)
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2011 Apple Inc. All rights reserved.
  * Copyright (C) 2009 Google Inc. All rights reserved.
  * Copyright (C) 2009 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.com/)
  *
  * This library is free software; you can redistribute it and/or
@@ skipping 740 matching lines @@
 
     bool simplifiedNormalFlowLayout = needsSimplifiedNormalFlowLayout() && !selfNeedsLayout() && !normalChildNeedsLayout();
 
     while (object) {
         if (object->selfNeedsLayout())
             return;
 
         // Don't mark the outermost object of an unrooted subtree. That object will be
         // marked when the subtree is added to the document.
         LayoutObject* container = object->container();
-        if (!container && !object->isLayoutView())
+        if (!container && !(object->isLayoutView() || object->isPositioned()))
             return;
         if (!last->isTextOrSVGChild() && last->style()->hasOutOfFlowPosition()) {
             bool willSkipRelativelyPositionedInlines = !object->isLayoutBlock() || object->isAnonymousBlock();
             // Skip relatively positioned inlines and anonymous blocks to get to the enclosing LayoutBlock.
             while (object && (!object->isLayoutBlock() || object->isAnonymousBlock()))
                 object = object->container();
             if (!object || object->posChildNeedsLayout())
                 return;
             if (willSkipRelativelyPositionedInlines)
                 container = object->container();
@@ skipping 2528 matching lines @@
         const blink::LayoutObject* root = object1;
         while (root->parent())
             root = root->parent();
         root->showLayoutTreeAndMark(object1, "*", object2, "-", 0);
     } else {
         fprintf(stderr, "Cannot showLayoutTree. Root is (nil)\n");
     }
 }
 
 #endif