test(watchGroup): fix incorrect expectations
test(watchGroup): fix incorrect expectations

watchGrp.detectChanges() returns the number of changes and as such can
never be null

winstonewert/angular.dart,giovannicandido/angular.dart,trinarytree/angular.dart,ronlobo/angular.dart,SibuStephen/angular.dart,rkirov/angular.dart,winstonewert/angular.dart,giovannicandido/angular.dart,rkirov/angular.dart,rkirov/angular.dart,trinarytree/angular.dart,hitesh97/angular.dart,SibuStephen/angular.dart,hitesh97/angular.dart,rkirov/angular.dart,ronlobo/angular.dart,hitesh97/angular.dart,hitesh97/angular.dart,trinarytree/angular.dart,ronlobo/angular.dart,ronlobo/angular.dart,SibuStephen/angular.dart,trinarytree/angular.dart,SibuStephen/angular.dart,winstonewert/angular.dart,giovannicandido/angular.dart,winstonewert/angular.dart