Fullscreen content should cover the entire screen

[manuq]

Right now, changing a video to fullscreen makes it cover the whole app window, not the whole screen:

Same happens with other content kind in fullscreen, like HTML5 apps.

Navigating to the same content with a browser in localhost, fullscreen works as expected.

[Dylan McCall]

I wish I could point to the specific commit where this was resolved, but, this has been resolved in v2.0. It's probably due to the Application refactor in #59, which (among other things) improved some earlier work in #8 that had added a handler for WebKit2.WebView's "create" signal.