cc: @greggman @Kangz

Previews, as seen when this build job started (823f156):
WebGPU _{webgpu.idl | Explainer | Correspondence Reference}
WGSL _{grammar.js | wgsl.lalr.txt}

For the record, this was where we said we couldn't use filtering with depth: #2094 (comment)

So FYI, in the WGSL spec there's this

https://gpuweb.github.io/gpuweb/wgsl/#texturesamplecompare

If the sampler uses bilinear filtering then the returned value is the filtered average of these values, otherwise the comparison result of a single texel is returned.

textureSampleCompare only takes depth textures so I guess the sentence above should be removed? Or leave it for someday when depth textures are allowed to be filtered since today the WebGPU spec disallows it.

Note: I was already testing this (averaging of depth texture compare values) and it seemed to be mostly working though not 100% sure it works everywhere. They've been filtered out now.

Depth textures can definitely be used with filtering sampler_comparison. Maybe the spec text needs to explicitly exclude sampler_comparison since it only cares about sampler.

ah, ... hmmm. I think we need a table

correct?

yeah, that table seems correct. IMO just tweaking the language to specify it includes sampler but not sampler_comparison is enough though. I'll draft a PR.

(There was a second fix in #4949 but I don't think that one needs any tweak.)