Add reduce to Queue.

corelib/src/implementation/queue.dart

Index: corelib/src/implementation/queue.dart
diff --git a/corelib/src/implementation/queue.dart b/corelib/src/implementation/queue.dart
index 82e4dd094f51700948b26898b136372dc1544bd0..ef3c5ef1fa73ee53fff068aa10dbbe3ae01ced87 100644
--- a/corelib/src/implementation/queue.dart
+++ b/corelib/src/implementation/queue.dart
@@ -216,6 +216,10 @@ class DoubleLinkedQueue<E> implements Queue<E> {
     return other;
   }
 
+  Dynamic reduce(Dynamic initialValue,
+                 Dynamic combine(Dynamic previousValue, E element)) {
+    return Collections.reduce(this, initialValue, combine);
+  }
 
   Queue<E> filter(bool f(E element)) {
     Queue<E> other = new Queue<E>();