Add workaround for invalid non-bmp character measurements in SVG

third_party/WebKit/Source/core/layout/svg/SVGTextMetricsBuilder.cpp

Index: third_party/WebKit/Source/core/layout/svg/SVGTextMetricsBuilder.cpp
diff --git a/third_party/WebKit/Source/core/layout/svg/SVGTextMetricsBuilder.cpp b/third_party/WebKit/Source/core/layout/svg/SVGTextMetricsBuilder.cpp
index caabcbf1dfb00edb44535cf4e28a59edd3427c5d..1da27a460e421a1b887bbb2f80b4fb79477a185c 100644
--- a/third_party/WebKit/Source/core/layout/svg/SVGTextMetricsBuilder.cpp
+++ b/third_party/WebKit/Source/core/layout/svg/SVGTextMetricsBuilder.cpp
@@ -162,6 +162,12 @@ unsigned SVGTextMetricsCalculator::updateSubrunRangesForCurrentPosition()
         }
     }
 
+    // TODO(pdr): m_subrunRanges can be too short in the presence of invalid
+    // unicode characters (see: crbug.com/595960). This is a temporary
+    // workaround to ensure the returned index is valid for m_subrunRages.
+    if (positionInRun >= m_subrunRanges.size())
+        return 0;
+
     return positionInRun;
 }