Unergonomic type for `size` of GPUTextureDescriptor

[pietrovismara]

Accessing the properties of size in a GPUTextureDescriptor requires first casting it as a GPUExtent3DDictStrict:

const texture: GPUTextureDescriptor = {
  size: { width: 1, height: 2, depthOrArrayLayers: 2 }, // No TS error here
  usage: GPUTextureUsage.COPY_DST,
  format: navigator.gpu.getPreferredCanvasFormat()
};

texture.size.width // Property 'width' does not exist on type 'GPUExtent3DStrict'.
texture.size.depthOrArrayLayers // Property 'depthOrArrayLayers' does not exist on type 'GPUExtent3DStrict'.

const size = texture.size as GPUExtent3DDictStrict;

size.width // OK
size.depthOrArrayLayers // OK

I understand this is probably because size can either be an Iterable or an object, but this isn't very ergonomic.
Perhaps GPUTextureDescriptor could take an optional generic parameter to determine the type of size?

Either way allowing size to be a union type makes dynamically handling GPUTextureDescriptors more complicated than it should be, since it forces you to check the type first.

I realize this is more of a spec issue than a types issue, but ideally size should just have one type. The drawbacks of having to check at runtime if it's an object or Iterable far outweigh the convenience of defining it more concisely as an array.

[kainino0x]

I'm aware of a few other problems like this as well, see in particular Array vs Iterable
#14
darionco/bikeshed-to-ts#6 (linked from #99)

Right now the best way to deal with this is to simply not declare your own variables using the WebGPU types, but instead use inferred types:

const texture = {
  size: { width: 1, height: 2, depthOrArrayLayers: 2 },
  usage: GPUTextureUsage.COPY_DST,
  format: navigator.gpu.getPreferredCanvasFormat()
};

or custom types when you really need them, like GPUTextureDescriptor & { size: GPUExtent3DDictStrict }

[kainino0x]

Oh, and #29 is similar too.