ASSERTION FAILED: !m_overflow

third_party/WebKit/Source/core/layout/line/InlineBox.h

 /*
  * Copyright (C) 2003, 2004, 2005, 2006, 2007, 2009, 2010, 2011 Apple 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
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
  *
  * This library is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
@@ skipping 333 matching lines @@
         void setBidiEmbeddingLevel(unsigned char bidiEmbeddingLevel) { m_bidiEmbeddingLevel = bidiEmbeddingLevel; }
 
         ADD_BOOLEAN_BITFIELD(dirty, Dirty);
         ADD_BOOLEAN_BITFIELD(extracted, Extracted);
         ADD_BOOLEAN_BITFIELD(hasVirtualLogicalHeight, HasVirtualLogicalHeight);
         ADD_BOOLEAN_BITFIELD(isHorizontal, IsHorizontal);
         // for RootInlineBox
         ADD_BOOLEAN_BITFIELD(endsWithBreak, EndsWithBreak); // Whether the line ends with a <br>.
         // shared between RootInlineBox and InlineTextBox
         ADD_BOOLEAN_BITFIELD(hasSelectedChildrenOrCanHaveLeadingExpansion, HasSelectedChildrenOrCanHaveLeadingExpansion);
+
+        // This boolean tracks whether we know that this box has no overflow.

[leviw_travelin_and_unemployed, 2015/11/13 00:40:33]

Nit: I wouldn't even bother with this first line now that the rest of your
comment does a good job or wrapping up what this means.

[Julien - ping for review, 2015/11/13 02:08:26]

Fair, removed.

+        //
+        // This boolean will never be set if there is potential for overflow,
+        // but it will be eagerly cleared in the opposite case. As such, it's
+        // a conservative tracking of the absence of overflow.
+        //
+        // For whether we have overflow, callers should use m_overflow on
+        // InlineFlowBox.
         ADD_BOOLEAN_BITFIELD(knownToHaveNoOverflow, KnownToHaveNoOverflow);
         ADD_BOOLEAN_BITFIELD(hasEllipsisBoxOrHyphen, HasEllipsisBoxOrHyphen);
         // for InlineTextBox
         ADD_BOOLEAN_BITFIELD(dirOverride, DirOverride);
         ADD_BOOLEAN_BITFIELD(isText, IsText); // Whether or not this object represents text with a non-zero height. Includes non-image list markers, text boxes.
 
     private:
         mutable unsigned m_determinedIfNextOnLineExists : 1;
 
     public:
@@ skipping 79 matching lines @@
 
 } // namespace blink
 
 #ifndef NDEBUG
 // Outside the WebCore namespace for ease of invocation from gdb.
 void showTree(const blink::InlineBox*);
 void showLineTree(const blink::InlineBox*);
 #endif
 
 #endif // InlineBox_h