Clear box from percentage descendants when it is split off from the ancestor

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

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2007 David Smith (catfish.man@gmail.com)
  * Copyright (C) 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011 Apple Inc. All rights reserved.
  * Copyright (C) Research In Motion Limited 2010. 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
  * License as published by the Free Software Foundation; either
@@ skipping 636 matching lines @@
     // If we make an object's children inline we are going to frustrate any future attempts to remove
     // floats from its children's float-lists before the next layout happens so clear down all the floatlists
     // now - they will be rebuilt at layout.
     toLayoutBlockFlow(this)->removeFloatingObjectsFromDescendants();
 
     for (size_t i = 0; i < blocksToRemove.size(); i++)
         collapseAnonymousBlockChild(this, blocksToRemove[i]);
     setChildrenInline(true);
 }
 
+bool LayoutBlock::collapseLoneAnonymousBlock(LayoutBlock* child)
+{
+    if (!child->isAnonymousBlock())
+        return false;
+    if (child->beingDestroyed())

[mstensho (USE GERRIT), 2016/01/18 20:06:24]

Do you really need this? collapseAnonymousBlockChild() performs the same check
anyway. But you might end up returning true without the check, of course. Not
sure if that's a problem, though.

+        return false;
+    if (child->nextSibling() || child->continuation())

[mstensho (USE GERRIT), 2016/01/18 20:06:24]

Looks like we're missing a child->previousSibling() check. Not that it matters
with the current usage of this method, but this one's gonna sneak up on us from
behind at some point in the future when we least expect it. :)

+        return false;
+    LayoutBlock* parent = child->containingBlock();
+    if (parent->isRubyBase() || parent->isRubyRun())

[mstensho (USE GERRIT), 2016/01/18 20:06:24]

Ah... ruby, out of the blue. But I guess that's how it has to be. :( There's
canCollapseAnonymousBlockChild(), but no exception for ruby there...

+        return false;
+    collapseAnonymousBlockChild(parent, child);
+    return true;
+}
+
 void LayoutBlock::collapseAnonymousBlockChild(LayoutBlock* parent, LayoutBlock* child)
 {
     // It's possible that this block's destruction may have been triggered by the
     // child's removal. Just bail if the anonymous child block is already being
     // destroyed. See crbug.com/282088
     if (child->beingDestroyed())
         return;
     parent->setNeedsLayoutAndPrefWidthsRecalcAndFullPaintInvalidation(LayoutInvalidationReason::ChildAnonymousBlockChanged);
 
     child->moveAllChildrenTo(parent, child->nextSibling(), child->hasLayer());
@@ skipping 2244 matching lines @@
 void LayoutBlock::showLineTreeAndMark(const InlineBox* markedBox1, const char* markedLabel1, const InlineBox* markedBox2, const char* markedLabel2, const LayoutObject* obj) const
 {
     showLayoutObject();
     for (const RootInlineBox* root = firstRootBox(); root; root = root->nextRootBox())
         root->showLineTreeAndMark(markedBox1, markedLabel1, markedBox2, markedLabel2, obj, 1);
 }
 
 #endif
 
 } // namespace blink