test(windowTime): add test asserting window Subject is disposed
test(windowTime): add test asserting window Subject is disposed

Add test for windowTime, to verify that every window Subject is disposed when the outer Observable
is unsubscribed.

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