Implement FusedStream and FusedFuture for Interval and Delay (#1476)

tokio-timer/src/interval.rs

@@ -100,6 +100,13 @@ impl Interval {
     }
 }
 
+#[cfg(feature = "async-traits")]
+impl futures_core::FusedStream for Interval {
+    fn is_terminated(&self) -> bool {
+        false
+    }
+}
+
 #[cfg(feature = "async-traits")]
 impl futures_core::Stream for Interval {
     type Item = Instant;