Fix failure to animate away exiting AppWindowToken

A previous check in changed the collection we were pulling exiting
AppWindowTokens from. Instead of pulling them from mExitingAppTokens
they came from mAppTokens and hence were not animated away.

Fixes bug 6296433.

Change-Id: I23347085658fce5412abb8ea119ce7e6152cab8b

Author: Craig Mautner

services/java/com/android/server/wm/WindowAnimator.java

@@ -139,7 +139,7 @@ private void updateWindowsAppsAndRotationAnimationsLocked() {
 
         final int NEAT = mService.mExitingAppTokens.size();
         for (i=0; i<NEAT; i++) {
-            final AppWindowAnimator appAnimator = mService.mAppTokens.get(i).mAppAnimator;
+            final AppWindowAnimator appAnimator = mService.mExitingAppTokens.get(i).mAppAnimator;
             final boolean wasAnimating = appAnimator.animation != null
                     && appAnimator.animation != WindowManagerService.sDummyAnimation;
             if (appAnimator.stepAnimationLocked(mCurrentTime, mInnerDw, mInnerDh)) {