Ensure that pixel buffer format is supported in RemoteRenderingBackend::getPixelBufferForImageBuffer.
rdar://89611041
Pull request: https://github.com/WebKit/WebKit/pull/1260
Committed r295170 (251254@main): <https://commits.webkit.org/251254@main> Reviewed commits have been landed. Closing PR #1260 and removing active labels.