test(select): add test of updating the model because of ng-change

A regression #7855 was introduced by
https://github.com/angular/angular.js/commit/dc149de9364c66b988f169f67cad39577ba43434
This test ensures that reverting that commit fixes this regression.
In the regression, changes to a bound model in ng-change were not propagated back to the view.

Test for #7855