[LayoutNG] Misc fixes in ShapingLineBreaker

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

Index: third_party/WebKit/Source/platform/fonts/shaping/HarfBuzzShaper.cpp
diff --git a/third_party/WebKit/Source/platform/fonts/shaping/HarfBuzzShaper.cpp b/third_party/WebKit/Source/platform/fonts/shaping/HarfBuzzShaper.cpp
index 8ceb11b94d29ca01b7c18343d4d8d122891d495e..ee7ce043a66a001117b7981da386b86cf749c958 100644
--- a/third_party/WebKit/Source/platform/fonts/shaping/HarfBuzzShaper.cpp
+++ b/third_party/WebKit/Source/platform/fonts/shaping/HarfBuzzShaper.cpp
@@ -713,6 +713,8 @@ PassRefPtr<ShapeResult> HarfBuzzShaper::Shape(const Font* font,
     if (start < segment_range.end && end > segment_range.start)
       ShapeSegment(&range_data, segment_range, result.Get());
   }
+  DCHECK(!result->NumCharacters() || (start == result->StartIndexForResult() &&
+                                      end == result->EndIndexForResult()));
   return result.Release();
 }