Currently webViewDidClose: checks self.hasOpener flag and ignores the callback if opener exists. Ignoring the callback may put WebKit into incorrect state, because WebKit expects the window to be closed. WebKit should only call webViewDidClose: if the window has opener (thought WebKit may have bugs and mistakenly think that there is an opener).

Unconditionally closing the window will not allow chrome to restore hasOpener flag after WKWebView is killed, but that's the right thing to do for webViewDidClose: API contract.