Fixing flashing when animation the launch task.

- When we are setting the tasks during the initialization of the tasks,
  only animate if we are not awaiting the first layout (since those
  should override the existing layout).

Bug: 28701153
Change-Id: I4ccb38417df15f43408b2ae77708ba9de407e753

packages/SystemUI/src/com/android/systemui/recents/views/TaskStackView.java

@@ -1391,8 +1391,9 @@ public class TaskStackView extends FrameLayout implements TaskStack.TaskStackCal
         updateLayoutAlgorithm(true /* boundScroll */);
 
         // Animate all the tasks into place
-        relayoutTaskViews(new AnimationProps(DEFAULT_SYNC_STACK_DURATION,
-                Interpolators.FAST_OUT_SLOW_IN));
+        relayoutTaskViews(mAwaitingFirstLayout
+                ? AnimationProps.IMMEDIATE
+                : new AnimationProps(DEFAULT_SYNC_STACK_DURATION, Interpolators.FAST_OUT_SLOW_IN));
     }
 
     /**