Fix the firing of the ReachedSessionRestorationRenderTreeSizeThreshold milestone on iOS
https://bugs.webkit.org/show_bug.cgi?id=143394
Reviewed by Tim Horton.
A client reshuffle at some point broke the dispatch of the ReachedSessionRestorationRenderTreeSizeThreshold
milestone. Fix by using WebPageProxy::didLayout() to fire the milestone.
* UIProcess/ios/WebPageProxyIOS.mm:
(WebKit::WebPageProxy::didCommitLayerTree):
git-svn-id: https://svn.webkit.org/repository/webkit/trunk@182340
268f45cc-cd09-0410-ab3c-
d52691b4dbfc