Don't let anonymous boxes impede percentage resolution on children.

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
  * modify it under the terms of the GNU Library General Public
@@ skipping 2414 matching lines @@
     return -1;
 }
 
 bool LayoutBox::skipContainingBlockForPercentHeightCalculation(const LayoutBox* containingBlock) const
 {
     // If the writing mode of the containing block is orthogonal to ours, it means that we shouldn't
     // skip anything, since we're going to resolve the percentage height against a containing block *width*.
     if (isHorizontalWritingMode() != containingBlock->isHorizontalWritingMode())
         return false;
 
-    // Flow threads for multicol or paged overflow should be skipped. They are invisible to the DOM,
-    // and percent heights of children should be resolved against the multicol or paged container.
-    if (containingBlock->isLayoutFlowThread())
+    // Anonymous layout objects are invisible to the DOM, so whatever they're doing there, they
+    // should not impede percentage resolution on a child. Examples of such anonymous layout objects
+    // are multicol flow threads and ruby runs.
+    if (containingBlock->isAnonymous())
         return true;
 
-    // For quirks mode and anonymous blocks, we skip auto-height containingBlocks when computing percentages.
-    // For standards mode, we treat the percentage as auto if it has an auto-height containing block.
-    if (!document().inQuirksMode() && !containingBlock->isAnonymousBlock())
-        return false;
-
-    return !containingBlock->isTableCell() && !containingBlock->isOutOfFlowPositioned() && containingBlock->style()->logicalHeight().isAuto();
+    // For quirks mode, we skip most auto-height containing blocks when computing percentages.
+    return document().inQuirksMode() && !containingBlock->isTableCell() && !containingBlock->isOutOfFlowPositioned() && containingBlock->style()->logicalHeight().isAuto();
 }
 
 LayoutUnit LayoutBox::computePercentageLogicalHeight(const Length& height) const
 {
     LayoutUnit availableHeight = -1;
 
     bool skippedAutoHeightContainingBlock = false;
     LayoutBlock* cb = containingBlock();
     const LayoutBox* containingBlockChild = this;
     LayoutUnit rootMarginBorderPaddingHeight = 0;
@@ skipping 2337 matching lines @@
 bool LayoutBox::canRenderBorderImage() const
 {
     if (!style()->hasBorderDecoration())
         return false;
 
     StyleImage* borderImage = style()->borderImage().image();
     return borderImage && borderImage->canRender(*this, style()->effectiveZoom()) && borderImage->isLoaded();
 }
 
 } // namespace blink