Fullscreen button should be removed or greyed out when fullscreen is unavailable

[DoomTay]

Description

See title.

Example use case: an iframe that doesn't have the allowfullscreen attribute. The given starter template is such an example

Results

Expected

Fullscreen button should be removed or greyed out

Actual

Fullscreen button appears functional, but clicking on it does nothing. It takes looking at the console to see that it's because the containing iframe doesn't have the allowfullscreen attribute

Error output

If there are any errors at all, please include them here.

Additional Information

Please include any additional information necessary here. Including the following:

versions

videojs

7.0.5

browsers

Firefox 60.0.2

OSes

Windows 10

plugins

None

[gkatsev]

Looks like we can check document.fullscreenEnabled and the vendor prefixed versions of that to know whether fullscreen is enabled or not.
Looks like we already get the correct prefix in our fullscreen-api file (sample usage, so, we can just use that either in the fullscreen-toggle file to disable it and grey it out (making sure to apply correct aria labels) or just removing it from the default components. I'm leaning towards disabling it rather than removing the button.

Would you be interested in making the change?

[DoomTay]

Sure, sounds pretty simple