Fix crash in which elementData() might be null.

Source/core/svg/SVGAnimateElement.cpp

Index: Source/core/svg/SVGAnimateElement.cpp
diff --git a/Source/core/svg/SVGAnimateElement.cpp b/Source/core/svg/SVGAnimateElement.cpp
index df0ffceb40bae5f0358658e46009d005c3e8cf87..c02ef6b60718c1ad1a1dae7bed1d446382417c8d 100644
--- a/Source/core/svg/SVGAnimateElement.cpp
+++ b/Source/core/svg/SVGAnimateElement.cpp
@@ -294,6 +294,7 @@ static inline void removeCSSPropertyFromTargetAndInstances(SVGElement* targetEle
 static inline void notifyTargetAboutAnimValChange(SVGElement* targetElement, const QualifiedName& attributeName)
 {
     ASSERT_WITH_SECURITY_IMPLICATION(!targetElement->m_deletionHasBegun);
+    targetElement->invalidateSVGAttributes();
     targetElement->svgAttributeChanged(attributeName);
 }