[WebGPU] Unify Surface and SwapChin into a single class
<rdar://problem/104729119>
Pull request: https://github.com/WebKit/WebKit/pull/9206
*** Bug 250962 has been marked as a duplicate of this bug. ***
*** Bug 250990 has been marked as a duplicate of this bug. ***
Committed 259508@main (b89163ea8850): <https://commits.webkit.org/259508@main> Reviewed commits have been landed. Closing PR #9206 and removing active labels.