refactor(core): allow animationend to process if we don't have a longest animation (angular#64225)

There may be cases where the longest animation info has been cleaned up before the end animation fires. We should still do the end processing in that case.

PR Close angular#64225

Author: thePunderWoman

packages/core/src/animation/utils.ts

@@ -233,9 +233,11 @@ export function isLongestAnimation(
   nativeElement: HTMLElement,
 ): boolean {
   const longestAnimation = longestAnimations.get(nativeElement);
+  // If we don't have any record of a longest animation, then we shouldn't
+  // block the animationend/transitionend event from doing its work.
+  if (longestAnimation === undefined) return true;
   return (
     nativeElement === event.target &&
-    longestAnimation !== undefined &&
     ((longestAnimation.animationName !== undefined &&
       (event as AnimationEvent).animationName === longestAnimation.animationName) ||
       (longestAnimation.propertyName !== undefined &&