fitMode doesn't work on video textures

[marcusx2]

If you fork this project and attempt to set the fit mode to cover for example, it won't work. The video will not play on the UI according to the fit mode you chose. It works with static images just fine, but it seems that on textures that are updated at runtime, it fails.

[yaustar]

Expected:

Result:

Project repro: https://playcanvas.com/project/972307/overview/video-fitmode