Guard against invalid glyph shaping results

third_party/WebKit/Source/platform/fonts/shaping/CachingWordShaper.cpp

 /*
  * Copyright (C) 2015 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 105 matching lines @@
     return buffer.getCharacterRange(run.direction(), totalWidth, from, to);
 }
 
 Vector<CharacterRange> CachingWordShaper::individualCharacterRanges(
     const Font* font, const TextRun& run)
 {
     ShapeResultBuffer buffer;
     float totalWidth = shapeResultsForRun(m_shapeCache, font, run, nullptr,
         &buffer);
 
-    return buffer.individualCharacterRanges(run.direction(), totalWidth);
+    auto ranges = buffer.individualCharacterRanges(run.direction(), totalWidth);
+    // The shaper can fail to return glyph metrics for all characters (see
+    // crbug.com/613915 and crbug.com/615661) so add empty ranges to ensure all
+    // characters have an associated range.
+    while (ranges.size() < static_cast<unsigned>(run.length()))
+        ranges.append(CharacterRange(0, 0));
+    return ranges;
 }
 
 }; // namespace blink