Percent height in auto height containers no longer computes as auto

third_party/WebKit/Source/core/layout/LayoutBoxModelObject.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 Apple Inc. All rights reserved.
  * Copyright (C) 2010 Google Inc. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
@@ skipping 507 matching lines @@
         }
         p = p->parent();
     }
     return offset;
 }
 
 LayoutBlock* LayoutBoxModelObject::containingBlockForAutoHeightDetection(Length logicalHeight) const
 {
     // For percentage heights: The percentage is calculated with respect to the height of the generated box's
     // containing block. If the height of the containing block is not specified explicitly (i.e., it depends
-    // on content height), and this element is not absolutely positioned, the value computes to 'auto'.
+    // on content height), and this element is not absolutely positioned,  the used height is calculated
+    // as if 'auto' was specified.
     if (!logicalHeight.hasPercent() || isOutOfFlowPositioned())
         return nullptr;
 
     // Anonymous block boxes are ignored when resolving percentage values that would refer to it:
     // the closest non-anonymous ancestor box is used instead.
     LayoutBlock* cb = containingBlock();
     while (cb->isAnonymous())
         cb = cb->containingBlock();
 
     // Matching LayoutBox::percentageLogicalHeightIsResolvableFromBlock() by
@@ skipping 430 matching lines @@
     if (rootElementStyle->hasBackground())
         return false;
 
     if (node() != document().firstBodyElement())
         return false;
 
     return true;
 }
 
 } // namespace blink