Fix null crash when creating KeyframeEffects with null targets

third_party/WebKit/Source/core/animation/KeyframeEffect.cpp

Index: third_party/WebKit/Source/core/animation/KeyframeEffect.cpp
diff --git a/third_party/WebKit/Source/core/animation/KeyframeEffect.cpp b/third_party/WebKit/Source/core/animation/KeyframeEffect.cpp
index 4f001bcf8c8b18f03b48da622c917912d0ac9116..cf5adcc5da02858f349eb4d5d1733c284b73012d 100644
--- a/third_party/WebKit/Source/core/animation/KeyframeEffect.cpp
+++ b/third_party/WebKit/Source/core/animation/KeyframeEffect.cpp
@@ -70,7 +70,8 @@ KeyframeEffect* KeyframeEffect::create(ExecutionContext* executionContext, Eleme
     if (element)
         UseCounter::count(element->document(), UseCounter::AnimationConstructorKeyframeListEffectObjectTiming);
     Timing timing;
-    if (!TimingInput::convert(timingInput, timing, &element->document(), exceptionState))
+    Document* document = element ? &element->document() : nullptr;
+    if (!TimingInput::convert(timingInput, timing, document, exceptionState))
         return nullptr;
     return create(element, EffectInput::convert(element, effectInput, executionContext, exceptionState), timing);
 }