Fix nullptr deref in InvalidateKeyframeEffect

third_party/WebKit/LayoutTests/animations/keyframeeffect-no-target-crash.html

Index: third_party/WebKit/LayoutTests/animations/keyframeeffect-no-target-crash.html
diff --git a/third_party/WebKit/LayoutTests/animations/keyframeeffect-no-target-crash.html b/third_party/WebKit/LayoutTests/animations/keyframeeffect-no-target-crash.html
new file mode 100644
index 0000000000000000000000000000000000000000..e411077837af446c7a916fe0188c8c37813a854d
--- /dev/null
+++ b/third_party/WebKit/LayoutTests/animations/keyframeeffect-no-target-crash.html
@@ -0,0 +1,16 @@
+<div id="target">This test passes if it does not crash.</div>
+<script>
+  let effect = new KeyframeEffect(null, null, {duration: 1000});
+  let animation = new Animation(effect);
+
+  if (window.testRunner) {
+    testRunner.waitUntilDone();
+    testRunner.dumpAsText();
+    requestAnimationFrame(function() {
+      testRunner.notifyDone();
+    });
+  }
+</script>
+<style>
+@keyframes frame { }
+</style>