Ensure ArrowPopup alpha is set to 1 at the end of the opening animation.

The fade in animation doesn't change the alpha until the reveal animation
has started — so when animators are turned off the alpha never gets updated.

Bug: 124252507
Change-Id: I19bb77e16389ff870e05692b1aea8483033485ac

src/com/android/launcher3/popup/ArrowPopup.java

@@ -384,6 +384,7 @@ public abstract class ArrowPopup extends AbstractFloatingView {
         openAnim.addListener(new AnimatorListenerAdapter() {
             @Override
             public void onAnimationEnd(Animator animation) {
+                setAlpha(1f);
                 announceAccessibilityChanges();
                 mOpenCloseAnimator = null;
             }