WebGLTextures: More flexible image dimensions computation.

[Mugen87]

Fixed #23164.
Fixed #27783.

Description

The above issues convinced me to make the renderer a bit more flexible in the way it derives image dimensions. This PR introduces a new function in WebGLTextures called getDimensions() that derives the image dimensions depending on the image type. So width and height are still the defaults but instances of HTMLImageElement now use naturalWidth and naturalHeight if available. Instances of VideoFrame are now supported by using displayWidth and displayHeight.

To minimize the change set, getDimensions() is only used at places in WebGLTextures where instances of HTMLImageElement or VideoFrame can actually occur. So e.g. not in the code paths for data or compressed textures.

[github-actions]

📦 Bundle size

Full ESM build, minified and gzipped.

Filesize dev	Filesize PR	Diff
678.1 kB (168.6 kB)	678.6 kB (168.7 kB)	+440 B

🌳 Bundle size after tree-shaking

Minimal build including a renderer, camera, empty scene, and dependencies.

Filesize dev	Filesize PR	Diff
458.5 kB (111.3 kB)	458.9 kB (111.4 kB)	+450 B

[Mugen87]

Side note: If it turns out in production that this change works well, we can adapt the same policy to WebGPURenderer.