fix(window): handle closingNotifier errors/completes

Fix window operator to handle error() and complete() notifications
happening on the closingNotifier Observable given as parameter to
window. This is important in order to pass all tests (that mirror RxJS
legacy tests).

src/operators/window.ts

@@ -62,4 +62,12 @@ class WindowClosingNotifierSubscriber<T> extends Subscriber<T> {
   _next() {
     this.parent.openWindow();
   }
+
+  _error(err: any) {
+    this.parent._error(err);
+  }
+
+  _complete() {
+    this.parent._complete();
+  }
 }