Fix debug crash when compositing keyword animations together

third_party/WebKit/Source/core/animation/CSSValueInterpolationType.h

Index: third_party/WebKit/Source/core/animation/CSSValueInterpolationType.h
diff --git a/third_party/WebKit/Source/core/animation/CSSValueInterpolationType.h b/third_party/WebKit/Source/core/animation/CSSValueInterpolationType.h
index 9d8ac2ee001d12905caca632253685b929b3278e..51c349049a6b8e176dfdd72e0667df9a0ed9567e 100644
--- a/third_party/WebKit/Source/core/animation/CSSValueInterpolationType.h
+++ b/third_party/WebKit/Source/core/animation/CSSValueInterpolationType.h
@@ -29,6 +29,11 @@ public:
         return nullptr;
     }
 
+    void composite(UnderlyingValue& underlyingValue, double underlyingFraction, const InterpolationValue& value) const final
+    {
+        underlyingValue.set(&value);
+    }
+
     void apply(const InterpolableValue&, const NonInterpolableValue*, StyleResolverState&) const final;
 };