Remove webgl2 render pass viewport workaround

[beicause]

Objective

The webgl2 workaround is added in #4967. It's old, and I didn't find any issues with the split_screen example on webgl2 after removing the workaround.

Solution

Remove the webgl2 workaround

Testing

cargo r -p build-wasm-example split_screen

[mockersf]

The webgl2 workaround is added in #4967. It's old, and I didn't find any issues with the split_screen example on webgl2 after removing the workaround.

I would love to remove it, but I would prefer to confirm it's ok on several browsers / os first.

Could you list the ones you tested?

[beicause]

I tested Linux Chromium and Firefox, Android Chromium