[WebGPU] Align SurfaceDescriptor and SwapChainDescriptor with the spec and WebGPU.h
<rdar://problem/104539553>
Pull request: https://github.com/WebKit/WebKit/pull/8962
Committed 259312@main (ffc98ceb72ee): <https://commits.webkit.org/259312@main> Reviewed commits have been landed. Closing PR #8962 and removing active labels.