[WebGPU] Flesh out SwapChain's API
<rdar://problem/104537242>
Pull request: https://github.com/WebKit/WebKit/pull/8958
*** This bug has been marked as a duplicate of bug 251248 ***
I think I'm actually gonna resurrect this.
Pull request: https://github.com/WebKit/WebKit/pull/9263
Committed 259585@main (7d48787400be): <https://commits.webkit.org/259585@main> Reviewed commits have been landed. Closing PR #9263 and removing active labels.