Animate the dock divider appearance/disappearance.

We want to animate the dock divider appearance only after the entrance
animation of the docked activity finishes, so these two don't clash. For
disappearance they will animate together.

Bug: 24913915
Change-Id: Ibe5c3960f21fcc5e64039b158605fa09017c5c34
diff --git a/services/core/java/com/android/server/wm/AppWindowToken.java b/services/core/java/com/android/server/wm/AppWindowToken.java
index 9143097..58ba24e 100644
--- a/services/core/java/com/android/server/wm/AppWindowToken.java
+++ b/services/core/java/com/android/server/wm/AppWindowToken.java
@@ -274,11 +274,11 @@
             // If we're animating with a saved surface, we're already visible.
             // Return true so that the alpha doesn't get cleared.
             if (!win.mAppFreezing
-                    && (win.mViewVisibility == View.VISIBLE
-                    || mAnimatingWithSavedSurface
-                    || (win.mWinAnimator.isAnimating() &&
-                            !service.mAppTransition.isTransitionSet()))
-                    && !win.mDestroying && win.isDrawnLw()) {
+                    && (win.mViewVisibility == View.VISIBLE || mAnimatingWithSavedSurface
+                            || (win.mWinAnimator.isAnimating()
+                                    && !service.mAppTransition.isTransitionSet()))
+                    && !win.mDestroying
+                    && win.isDrawnLw()) {
                 return true;
             }
         }