SingleViewHost: wait 2 frames before disabling rendering
SingleViewHost: wait 2 frames before disabling rendering

While testing some apps I noticed that the native view often does not appear on screen before 2 frames after adding it to the UI tree. This leads to 1 frame glitches (easily observed in ManualTestApp, focus and unfocus a TextInput/TextView). Fixed by disabling drawing after 2 frames.

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