CSSGradientValue should check whether gradientLength is zero or not.

Source/core/css/CSSGradientValue.cpp

Index: Source/core/css/CSSGradientValue.cpp
diff --git a/Source/core/css/CSSGradientValue.cpp b/Source/core/css/CSSGradientValue.cpp
index 0c6e578aac69a728e056d2bc82ffca7ecaeac8e5..5b7ea0b2892a6f02cfa71c77039f7fac5485097d 100644
--- a/Source/core/css/CSSGradientValue.cpp
+++ b/Source/core/css/CSSGradientValue.cpp
@@ -276,7 +276,7 @@ void CSSGradientValue::addStops(Gradient* gradient, RenderObject* renderer, Rend
                 }
 
                 if (maxLengthForRepeat > gradientLength)
-                    maxExtent = maxLengthForRepeat / gradientLength;
+                    maxExtent = gradientLength > 0 ? maxLengthForRepeat / gradientLength : 0;
             }
 
             size_t originalNumStops = numStops;