Don't send sync RemoteMediaPlayerProxy messages that we know will fail
rdar://86662565
Created attachment 455950 [details] Patch
Created attachment 455968 [details] Patch for landing
The failing iOS tests are unrelated.
Committed r292044 (248984@main): <https://commits.webkit.org/248984@main> All reviewed patches have been landed. Closing bug and clearing flags on attachment 455968 [details].