Shift visual-to-flowthread coordinate space conversion one level up in the tree.

third_party/WebKit/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 2279 matching lines @@
         } else if (o->isBox()) {
             applyContainerFlip = o->style()->isFlippedBlocksWritingMode();
             mode &= ~ApplyContainerFlip;
         }
     }
 
     if (!ancestorSkipped)
         o->mapAncestorToLocal(ancestor, transformState, mode);
 
     LayoutSize containerOffset = offsetFromContainer(o);
-    if (o->isLayoutFlowThread()) {
+    if (isLayoutFlowThread()) {
         // Descending into a flow thread. Convert to the local coordinate space, i.e. flow thread coordinates.
         LayoutPoint visualPoint = LayoutPoint(transformState.mappedPoint());
-        transformState.move(visualPoint - toLayoutFlowThread(o)->visualPointToFlowThreadPoint(visualPoint));
+        transformState.move(visualPoint - toLayoutFlowThread(this)->visualPointToFlowThreadPoint(visualPoint));
     }
 
     bool preserve3D = mode & UseTransforms && (o->style()->preserves3D() || style()->preserves3D());
     if (mode & UseTransforms && shouldUseTransformFromContainer(o)) {
         TransformationMatrix t;
         getTransformFromContainer(o, containerOffset, t);
         transformState.applyTransform(t, preserve3D ? TransformState::AccumulateTransform : TransformState::FlattenTransform);
     } else {
         transformState.move(containerOffset.width(), containerOffset.height(), preserve3D ? TransformState::AccumulateTransform : TransformState::FlattenTransform);
     }
@@ skipping 1371 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