Fullscreen controls inoperative in WebKitLegacy web views

Fullscreen controls inoperative in WebKitLegacy web views
https://bugs.webkit.org/show_bug.cgi?id=162374

Reviewed by Eric Carlson.

After r205365, the WebPlaybackSessionInterfaceAVKit was now created after the
WebPlaybackSessionModel which fed it data, so it no longer received the burst of data upon
creation. Instead, it should have always asked the model for its cached data as soon as it
was connected to set up its inital state.

* platform/ios/WebPlaybackSessionInterfaceAVKit.mm:
(WebCore::WebPlaybackSessionInterfaceAVKit::WebPlaybackSessionInterfaceAVKit):

git-svn-id: https://svn.webkit.org/repository/webkit/trunk@206272 268f45cc-cd09-0410-ab3c-d52691b4dbfc