Bug 1095832 - [RTL][Video] Progress slider position moves opposite from ...

...slider progress
I don't think it is necessary to put this in ready(). That would be a good idea if you were actually having to consult the DOM by querying document.documentElement.dir, but I htink navigator.mozL10n.language.direction is pure JS and should be quick to use. 

So I'd leave this ready() function alone and just use navigator.mozL10n.language.direction instead of languageDirection below.