Test that using documentPictureInPicture's preferInitialWindowPlacement parameter does not cache the window bounds

This tests that a document picture-in-picture window opened with the preferInitialWindowPlacement parameter set to true does not cache the previous window bounds when it is closed and reopened.

1. Click on the "Open document picture-in-picture window" button below.
2. Note its approximate position and size.
3. Move and resize the window.
4. Close the window.
5. Click the "Open document picture-in-picture window" button again.
6. Check that it opens in its original position and size, not where you resized / moved it to.