Force glyph overflow calculation

Source/core/layout/line/BreakingContextInlineHeaders.h

 /*
  * Copyright (C) 2000 Lars Knoll (knoll@kde.org)
  * Copyright (C) 2003, 2004, 2006, 2007, 2008, 2009, 2010, 2011 Apple Inc. All right reserved.
  * Copyright (C) 2010 Google Inc. All rights reserved.
  * Copyright (C) 2013 Adobe Systems Incorporated.
  *
  * 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.
@@ skipping 493 matching lines @@
 }
 
 ALWAYS_INLINE TextDirection textDirectionFromUnicode(WTF::Unicode::Direction direction)
 {
     return direction == WTF::Unicode::RightToLeft
         || direction == WTF::Unicode::RightToLeftArabic ? RTL : LTR;
 }
 
 ALWAYS_INLINE float textWidth(LayoutText* text, unsigned from, unsigned len, const Font& font, float xPos, bool collapseWhiteSpace, HashSet<const SimpleFontData*>* fallbackFonts = nullptr)
 {
-    GlyphOverflow glyphOverflow;
-    if ((!from && len == text->textLength()) || text->style()->hasTextCombine())
-        return text->width(from, len, font, xPos, text->style()->direction(), fallbackFonts, &glyphOverflow);
+    if ((!from && len == text->textLength()) || text->style()->hasTextCombine()) {
+        GlyphOverflow glyphOverflow;
+        return text->width(from, len, font, xPos, text->style()->direction(), fallbackFonts,
+            // LayoutText caches fallbackFonts and glyphOverflow together, and requires them to be both null or both non-null.
+            fallbackFonts ? &glyphOverflow : nullptr);
+    }
 
     TextRun run = constructTextRun(text, font, text, from, len, text->styleRef());
     run.setCodePath(text->canUseSimpleFontCodePath() ? TextRun::ForceSimple : TextRun::ForceComplex);
     run.setTabSize(!collapseWhiteSpace, text->style()->tabSize());
     run.setXPos(xPos);
-    return font.width(run, fallbackFonts, &glyphOverflow);
+    return font.width(run, fallbackFonts, nullptr);
 }
 
 inline bool BreakingContext::handleText(WordMeasurements& wordMeasurements, bool& hyphenated)
 {
     if (!m_current.offset())
         m_appliedStartWidth = false;
 
     LayoutText* layoutText = toLayoutText(m_current.object());
 
     bool isSVGText = layoutText->isSVGInlineText();
@@ skipping 366 matching lines @@
 
     if (style.textIndentType() == TextIndentHanging)
         shouldIndentText = shouldIndentText == IndentText ? DoNotIndentText : IndentText;
 
     return shouldIndentText;
 }
 
 }
 
 #endif // BreakingContextInlineHeaders_h