test(zip): subscription asserts for proto zip
test(zip): subscription asserts for proto zip

Add tests for Observable.prototype.zip that assert subscription and
unsubscription times. Also "normalize" the tests to contain all tests from
the static variant of zip.

jinroh/RxJS,robwormald/RxJS,SangKa/RxJS-Docs-CN,kwonoj/RxJS,ReactiveX/RxJS,RxJS-CN/RxJS-Docs-CN,gluck/RxJS,justinwoo/RxJS,adrianomelo/RxJS-1,staltz/RxJSNext,robwormald/RxJS,jadbox/RxJS,justinwoo/RxJS,figueredo/RxJS,benlesh/RxJS,RxJS-CN/RxJS-Docs-CN,Brocco/RxJS,IgorMinar/RxJS,elliotschi/rxjs,ReactiveX/RxJS,ReactiveX/rxjs,benlesh/RxJS,trxcllnt/RxJS,figueredo/RxJS,martinsik/rxjs,martinsik/rxjs,martinsik/rxjs,figueredo/RxJS,jinroh/RxJS,jayphelps/rxjs,jayphelps/rxjs,Igorbek/rxjs5,elliotschi/rxjs,justinwoo/RxJS,adrianomelo/RxJSNext,IgorMinar/RxJS,benlesh/RxJS,jadbox/RxJS,adrianomelo/RxJSNext,RxJS-CN/RxJS-Docs-CN,jayphelps/rxjs,Brocco/RxJS,mattpodwysocki/RxJS,justinwoo/RxJS,gluck/RxJS,adrianomelo/RxJS-1,ReactiveX/RxJS,ReactiveX/rxjs,Igorbek/rxjs5,adrianomelo/RxJS-1,jinroh/RxJS,Brocco/RxJS,adrianomelo/RxJSNext,Igorbek/rxjs5,gluck/RxJS,Igorbek/rxjs5,SangKa/RxJS-Docs-CN,SangKa/RxJS-Docs-CN,mattpodwysocki/RxJS,trxcllnt/RxJS,adrianomelo/RxJS-1,saneyuki/RxJS,jayphelps/rxjs,SangKa/RxJS-Docs-CN,staltz/RxJSNext,jinroh/RxJS,martinsik/rxjs,elliotschi/rxjs,mattpodwysocki/RxJS,trxcllnt/RxJS,Brocco/RxJS,ReactiveX/RxJS,saneyuki/RxJS,RxJS-CN/RxJS-Docs-CN,figueredo/RxJS,robwormald/RxJS,staltz/RxJSNext,kwonoj/RxJS,mattpodwysocki/RxJS,benlesh/RxJS,robwormald/RxJS,kwonoj/RxJS,jadbox/RxJS,kwonoj/RxJS,trxcllnt/RxJS,gluck/RxJS,elliotschi/rxjs,jayphelps/rxjs,ReactiveX/rxjs,adrianomelo/RxJSNext,jadbox/RxJS,staltz/RxJSNext,ReactiveX/rxjs