Description
Several times while using this widget, I've had focus on the country list, scrolled or typed to a country and hit Tab intending to select the highlighted entry. But instead of choosing the entry I had reached, it just closed the dropdown and focused the phone input. I had to go back, find the country again and remember to hit Enter (or click) instead of Tab.
The country list is not a "real" select control, but users will expect it to perform similarly. In a native select, the Tab behavior is not universal across browsers, but it's consistent enough that I think there's a case to be made for making Tab select. In Firefox and IE, selecting with the arrow keys visibly changes the item in the control and commits that change when you tab. However, those browsers don't select when you tab from a mouseover. Chrome on the other hand doesn't preview a change to the item, but Tab selects the highlighted item whether you arrowed to it or moused over it.
It'd be nice if there were a standardized behavior to track, but in the absence of one, I think that adding select-on-tab is a reasonable compromise that's going to surprise fewer people than the current behavior. (Previewing the selection is not necessary and would be more complicated to emulate.)
This would be a very minor change. I will submit a PR for it.