4913: Can't slide volume slider in pop out mode
I first tried to handle this at the floating player level, but it was impossible to hack there due to how 'react-draggable' works (it already moved the window before the "move" handler is called, so we can't do much).
Fix by overriding the dragging behavior of the videojs' VolumeBar class by not propagating the event further. It is odd that videojs didn't already do this, since it's SeekBar does stop the propagation.
18debf51cd