Move SleepDisabler ownership from WebProcessProxy to WebPageProxy. Those "sleep disabling" assertion are taken by paging and it thus makes sense for their lifetime to be tired to the page rather than the process. This tighter scoping reduces the chances of assertion leakage and fit nicely with our UIProcess-side logic now that we rely on the UIClient to take some of these assertions.
Pull request: https://github.com/WebKit/WebKit/pull/13245
Committed 263474@main (9bfa2b8cde5b): <https://commits.webkit.org/263474@main> Reviewed commits have been landed. Closing PR #13245 and removing active labels.
<rdar://problem/108635306>