position:fixed content is not offset by relative positioned ancestors

third_party/WebKit/Source/core/layout/LayoutBox.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2005 Allan Sandfeld Jensen (kde@carewolf.com)
  *           (C) 2005, 2006 Samuel Weinig (sam.weinig@gmail.com)
  * Copyright (C) 2005, 2006, 2007, 2008, 2009, 2010 Apple Inc.
  *               All rights reserved.
  * Copyright (C) 2013 Adobe Systems Incorporated. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
@@ skipping 4152 matching lines @@
 
   // FIXME: The static distance computation has not been patched for mixed
   // writing modes.
   LayoutUnit staticLogicalTop = child->layer()->staticBlockPosition();
   for (LayoutObject* curr = child->parent(); curr && curr != containerBlock;
        curr = curr->container()) {
     if (!curr->isBox() || curr->isTableRow())
       continue;
     const LayoutBox& box = *toLayoutBox(curr);
     staticLogicalTop += box.logicalTop();
+    if (box.isInFlowPositioned())
+      staticLogicalTop += box.offsetForInFlowPosition().height();
     if (!box.isLayoutFlowThread())
       continue;
     // We're walking out of a flowthread here. This flow thread is not in the
     // containing block chain, so we need to convert the position from the
     // coordinate space of this flowthread to the containing coordinate space.
     // The inline position cannot affect the block position, so we don't bother
     // calculating it.
     LayoutUnit dummyInlinePosition;
     toLayoutFlowThread(box).flowThreadToContainingCoordinateSpace(
         staticLogicalTop, dummyInlinePosition);
@@ skipping 1484 matching lines @@
     block->adjustChildDebugRect(rect);
 
   return rect;
 }
 
 bool LayoutBox::shouldClipOverflow() const {
   return hasOverflowClip() || styleRef().containsPaint() || hasControlClip();
 }
 
 }  // namespace blink