Fix tap-through during screenshot dismissal

We were removing the onComputeInternalInsetsListener at the start
of the dismissal animation, which broke tap-through during
dismissal. We remove the listener after dismissal anyway, so just
wait until then.

Bug: 191981223
Bug: 191981223
Test: manual (helps to have window animation scale (slow) on)
Change-Id: I4cbf9376f8646904ed991aec55faeb271826684a

packages/SystemUI/src/com/android/systemui/screenshot/ScreenshotView.java

@@ -865,10 +865,6 @@ public class ScreenshotView extends FrameLayout implements
     }
 
     private void animateDismissal(Animator dismissAnimation) {
-        if (DEBUG_WINDOW) {
-            Log.d(TAG, "removing OnComputeInternalInsetsListener");
-        }
-        getViewTreeObserver().removeOnComputeInternalInsetsListener(this);
         mDismissAnimation = dismissAnimation;
         mDismissAnimation.addListener(new AnimatorListenerAdapter() {
             private boolean mCancelled = false;