`flipY` doesn't work when using image bitmaps

[jsonkao]

Description

Using flipY has no effect when using ImageBitmaps.

To Reproduce

Here's a repository (jsonkao/regl-bitmap-flipy-broken) showing the problem.

There are two functions in main.js loading the same image. One retrieves the bitmap, the other retrieves the image object.

Currently, the code creates a texture from the image object (L26). But if we use the bitmap object (uncomment L28), we see that flipY doesn't do anything.

I've also tried using createImageBitmap on the image object itself instead of a Blob, but the issue persists.