Ensure we compute the min and max height of replaced elements to 'none' or 0 when appropriate.

Source/core/rendering/RenderBox.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
  * modify it under the terms of the GNU Library General Public
@@ skipping 2754 matching lines @@
 
     ASSERT_NOT_REACHED();
     return 0;
 }
 
 LayoutUnit RenderBox::computeReplacedLogicalHeight() const
 {
     return computeReplacedLogicalHeightRespectingMinMaxHeight(computeReplacedLogicalHeightUsing(style()->logicalHeight()));
 }
 
+bool RenderBox::logicalHeightComputesAsNone(SizeType sizeType) const
+{
+    ASSERT(sizeType == MinSize || sizeType == MaxSize);
+    Length logicalHeightLength = sizeType == MinSize ? style()->logicalMinHeight() : style()->logicalMaxHeight();

[esprehn, 2014/07/16 20:43:50]

Why suffix with Length?

+
+    if (logicalHeightLength == (sizeType == MinSize ? RenderStyle::initialMinSize() : RenderStyle::initialMaxSize()))

[esprehn, 2014/07/16 20:43:49]

Can we put this in a stack var instead of inside the if?

Length initialHeight = sizeType == MinSize ? ....;

if (logicalHeight == initialHeight)
  return true;

+        return true;
+
+    if (!logicalHeightLength.isPercent() || isOutOfFlowPositioned())
+        return false;
+
+    // Anonymous block boxes are ignored when resolving percentage values that would refer to it:
+    // the closest non-anonymous ancestor box is used instead.
+    RenderBlock* cb = containingBlock();

[esprehn, 2014/07/16 20:43:50]

containingBlock = this->containingBlock() ? I'd be nice not to add more of these
two letter vars.

+    while (cb->isAnonymous())
+        cb = cb->containingBlock();
+
+    return cb->hasAutoHeightOrContainingBlockWithAutoHeight();
+}
+
 LayoutUnit RenderBox::computeReplacedLogicalHeightRespectingMinMaxHeight(LayoutUnit logicalHeight) const
 {
-    LayoutUnit minLogicalHeight = computeReplacedLogicalHeightUsing(style()->logicalMinHeight());
-    LayoutUnit maxLogicalHeight = style()->logicalMaxHeight().isUndefined() ? logicalHeight : computeReplacedLogicalHeightUsing(style()->logicalMaxHeight());
+    // 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 percentage value is treated as '0' (for 'min-height') or 'none' (for 'max-height').
+    LayoutUnit minLogicalHeight = logicalHeightComputesAsNone(MinSize) ? LayoutUnit() : computeReplacedLogicalHeightUsing(style()->logicalMinHeight());

[esprehn, 2014/07/16 20:43:49]

Instead of using a ternary I might early initialize.

LayoutUnit minLogicalHeight;
if (!logicalHeightComputesAsNone(MinSize))
  minLogicalHeight =
computeReplacedLogicalHeightUsing(style()->logicalMinHeight());

LayoutUnit maxLogicalHeight = logicalHeight;
if (!logicalHeightComputesAsNone(MaxSize))
  maxLogicalHeight =
computeReplacedLogicalHeightUsing(style()->logicalMaxHeight());

+    LayoutUnit maxLogicalHeight = logicalHeightComputesAsNone(MaxSize) ? logicalHeight : computeReplacedLogicalHeightUsing(style()->logicalMaxHeight());
     return std::max(minLogicalHeight, std::min(logicalHeight, maxLogicalHeight));
 }
 
 LayoutUnit RenderBox::computeReplacedLogicalHeightUsing(const Length& logicalHeight) const
 {
     switch (logicalHeight.type()) {
         case Fixed:
             return adjustContentBoxLogicalHeightForBoxSizing(logicalHeight.value());
         case Percent:
         case Calculated:
@@ skipping 1896 matching lines @@
         return 0;
 
     if (!layoutState && !flowThreadContainingBlock())
         return 0;
 
     RenderBlock* containerBlock = containingBlock();
     return containerBlock->offsetFromLogicalTopOfFirstPage() + logicalTop();
 }
 
 } // namespace WebCore