fix(modal): keyboard=false should not stop trapping tab focus.

[wawyed]

Fix for #4990

[wesleycho]

Can you add a test for this? Should be simple, just test when emitting the proper keypress event with event.which being 9, the esc key value, and testing whether it has been defaultPrevented.

[wawyed]

What would you like me to test? keyboard = false is already been tested by https://github.com/angular-ui/bootstrap/blob/master/src/modal/test/modal.spec.js#L747

[wesleycho]

Testing when hitting esc and making sure it isn't getting defaultPrevented normally is what I mean

[wawyed]

I'm a bit confused with what you mean. What does preventDefault have anything to do with my PR? The only test that I can think of adding would be that the trap focus on tab works correctly even when keyboard=false is used.

[wesleycho]

Ensuring that it isn't prevented is what I meant - the current behavior in master is that it will be prevented when tabbing (I got confused with the keycode heh).

[wawyed]

Made another PR with unit tests, #5010