If -[WKWebView _notifyUserScripts] is called early, before Frame::injectUserScripts() happens, pageWasNotified will still be false, allowing scripts to build up in m_userScriptsAwaitingNotification and never being injected (since -[WKWebView _notifyUserScripts] will not be called again).
Created attachment 395710 [details] Patch
<rdar://problem/61368446>
<rdar://problem/61401382>
Committed r259650: <https://trac.webkit.org/changeset/259650> All reviewed patches have been landed. Closing bug and clearing flags on attachment 395710 [details].