[WebEngine Video Player] ESC key enters into fullscreen mode

Steps to reproduce:

1. Open Example and build for 'Desktop Qt 5.15.15 clang 64-bit'
2. Play the video
3. Enter fullscreen using Mac window toggle
4. Press the fullscreen button at the bottom right of youtube player
5. Exit fullscreen using Mac window toggle
6. After exiting fullscreen, press ESC key 

Actual Results:{}

Pressing ESC key, enters fullscreen mode.

Expected Results:

It should remain in normal mode only.

Reproducibility:  100%