Android Keyboard shortcuts support

[aronicmoe]

In Firefox android: you can't do `Ctrl+T` to create a new Tab, `Ctrl+W` to close te current tab, `Ctrl+Shift+T` to reopen closed tab. I really want to switch to Firefox on my Tablet because of Sync, and this QoL features will really be appreciated.

[Jon]

Thanks for submitting an idea to the Mozilla Connect community! Your idea is now open to votes (aka kudos) and comments.

[Miles_Nguyen]

greatly appreciate your idea. I have the same in mind as well