fix: make fakeAsync test spec timer id global (#1207)
fix: make fakeAsync test spec timer id global (#1207)

There is a possibility that a single test gets timer id-s from two
separate fakeAsync test zones and the id-s could clash.

This changes makes it such that the next timer id is global and the can
never clash.
angular/zone.js,angular/zone.js,angular/zone.js,angular/zone.js,angular/zone.js