Removes unused(?) source field in OperatorDelay

Author: hyleung

src/main/java/rx/Observable.java

@@ -4127,7 +4127,7 @@ public final Observable<T> delay(long delay, TimeUnit unit) {
      * @see <a href="http://reactivex.io/documentation/operators/delay.html">ReactiveX operators documentation: Delay</a>
      */
     public final Observable<T> delay(long delay, TimeUnit unit, Scheduler scheduler) {
-        return lift(new OperatorDelay<T>(this, delay, unit, scheduler));
+        return lift(new OperatorDelay<T>(delay, unit, scheduler));
     }
 
     /**

src/main/java/rx/internal/operators/OperatorDelay.java

@@ -32,13 +32,11 @@
  */
 public final class OperatorDelay<T> implements Operator<T, T> {
 
-    final Observable<? extends T> source;
     final long delay;
     final TimeUnit unit;
     final Scheduler scheduler;
 
-    public OperatorDelay(Observable<? extends T> source, long delay, TimeUnit unit, Scheduler scheduler) {
-        this.source = source;
+    public OperatorDelay(long delay, TimeUnit unit, Scheduler scheduler) {
         this.delay = delay;
         this.unit = unit;
         this.scheduler = scheduler;