remove a typo

Summary:
I can't guess the point. Just simply removed this typo.
Closes https://github.com/facebook/react-native/pull/4943

Reviewed By: svcscm

Differential Revision: D2786863

Pulled By: bestander

fb-gh-sync-id: 0f36f796cae23bacb86ffe224b6b05915e228f47

Libraries/Animated/src/AnimatedImplementation.js

@@ -577,7 +577,7 @@ class AnimatedValue extends AnimatedWithChildren {
 
   /**
    * Adds an asynchronous listener to the value so you can observe updates from
-   * animations or whathaveyou.  This is useful because there is no way to
+   * animations.  This is useful because there is no way to
    * synchronously read the value because it might be driven natively.
    */
   addListener(callback: ValueListenerCallback): string {