Remove the ability to switch language to the current language

The "Restart brackets" button will be disabled if you select the current
lang in the "Switch Language" dialog.

Tested on Windows 8 with Brackets 0.32 master c05cfd5
Fixed indent
Update main.js

Thanks for the tip ;)
Merge pull request #5287 from SAPlayer/patch-5

Remove the ability to switch language to the current language