Popup: blue focus flash on android 4.2

So I tested this with Browserstack on android 4.2 and it fixed the problem.  However, when I run "grunt test" there are a number of test cases failing.  @arschmitz suggested I do a pull request so he can take a look.  So don't merge if it's breaking tests! :)
Since we no longer add the tabindex attribute, we must remove the code that removes it from ```_destroy()```.