This PR changes Web IDL interfaces to be declared with `var` instead of
`class`, so that accessing them via `globalThis` does not raise type
errors.
Closes #13390.
This PR _**temporarily**_ removes WebGPU (which has behind the
`--unstable` flag in Deno), due to performance complications due to its
presence.
It will be brought back in the future; as a point of reference, Chrome
will ship WebGPU to stable on 26/04/2023.
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Co-authored-by: Bartek Iwańczuk <biwanczuk@gmail.com>
