Extend Iterable instead of implementing it.

sdk/lib/_internal/compiler/implementation/tree/nodes.dart

Index: sdk/lib/_internal/compiler/implementation/tree/nodes.dart
diff --git a/sdk/lib/_internal/compiler/implementation/tree/nodes.dart b/sdk/lib/_internal/compiler/implementation/tree/nodes.dart
index 99d3a88876f3758fd7586a1f1e29827a5afd3189..f2a2d955c92734c730da37bf9113f7e350d7388f 100644
--- a/sdk/lib/_internal/compiler/implementation/tree/nodes.dart
+++ b/sdk/lib/_internal/compiler/implementation/tree/nodes.dart
@@ -466,6 +466,54 @@ class NodeList extends Node implements Iterable<Node> {
     }
     return beginToken;
   }
+
+  // ------------------- Iterable methods -------------------------------------
+  //
+  // TODO(floitsch): these functions should be pulled in through a mixin
+  // mechanism.
+  Collection mappedBy(f(Node element)) {
+    List result = [];
+    for (Node element in this) result.add(f(element));
+    return result;
+  }
+
+  Collection<Node> where(bool f(Node element)) {
+    List result = <Node>[];
+    for (Node element in this) if (f(element)) result.add(element);
+    return result;
+  }
+
+  bool contains(Node element) {
+    for (Node e in this) {
+      if (e == element) return true;
+    }
+    return false;
+  }
+
+  void forEach(void f(Node element)) {
+    for (Node element in this) f(element);
+  }
+
+  dynamic reduce(var initialValue,
+                 dynamic combine(var previousValue, Node element)) {
+    var value = initialValue;
+    for (Node element in this) value = combine(value, element);
+    return value;
+  }
+
+  bool every(bool f(Node element)) {
+    for (Node element in this) {
+      if (!f(element)) return false;
+    }
+    return true;
+  }
+
+  bool some(bool f(Node element)) {
+    for (Node element in this) {
+      if (f(element)) return true;
+    }
+    return false;
+  }
 }
 
 class Block extends Statement {