test(select): add test cases for selects with blank disabled options
test(select): add test cases for selects with blank disabled options

An earlier commit 866968c033d1b03efbf16c7ac03304a20d5561ea caused an error where the first option of
a select would be skipped over if it had a blank disabled value. These tests demonstrate that with
that commit in place, blank disabled options are skipped in a select. When the commit is reverted,
the correct behavior is seen that the blank disabled option is still selected in both selects
marked with required and those that have optional choices.

Relates to #7715

ggershoni/angular.js,ggershoni/angular.js,ggershoni/angular.js,ggershoni/angular.js