fix(windowTime): fix windowTime to dispose window Subjects

Fix windowTime() operator to dispose window Subjects when the destination Subscriber is
unsubscribed.

src/operator/windowTime.ts

@@ -19,7 +19,7 @@ class WindowTimeOperator<T, R> implements Operator<T, R> {
  private scheduler: Scheduler) {
  }
 
- call(subscriber: Subscriber<T>): Subscriber<T> {
+ call(subscriber: Subscriber<Observable<T>>): Subscriber<T> {
  return new WindowTimeSubscriber(
  subscriber, this.windowTimeSpan, this.windowCreationInterval, this.scheduler
  );
@@ -29,7 +29,7 @@ class WindowTimeOperator<T, R> implements Operator<T, R> {
 class WindowTimeSubscriber<T> extends Subscriber<T> {
  private windows: Subject<T>[] = [];
 
- constructor(destination: Subscriber<T>,
+ constructor(protected destination: Subscriber<Observable<T>>,
  private windowTimeSpan: number,
  private windowCreationInterval: number,
  private scheduler: Scheduler) {
@@ -72,9 +72,11 @@ class WindowTimeSubscriber<T> extends Subscriber<T> {
  }
 
  openWindow(): Subject<T> {
- let window = new Subject<T>();
+ const window = new Subject<T>();
  this.windows.push(window);
- this.destination.next(window);
+ const destination = this.destination;
+ destination.add(window);
+ destination.next(window);
  return window;
  }