Implement super initializers.

frog/leg/tree/nodes.dart

 // Copyright (c) 2011, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 interface Visitor<R> {
   R visitBlock(Block node);
   R visitBreakStatement(BreakStatement node);
   R visitCatchBlock(CatchBlock node);
   R visitClassNode(ClassNode node);
   R visitConditional(Conditional node);
@@ skipping 1424 matching lines @@
 
   visitChildren(Visitor visitor) {
     formals.accept(visitor);
     block.accept(visitor);
   }
 
   Token getBeginToken() => catchKeyword;
 
   Token getEndToken() => block.getEndToken();
 }
+
+class Initializers {
+  static bool isSuperConstructorCall(Send node) {
+    return (node.receiver === null &&
+            node.selector.asIdentifier() !== null &&
+            node.selector.asIdentifier().isSuper()) ||
+           (node.receiver !== null &&
+            node.receiver.asIdentifier() !== null &&
+            node.receiver.asIdentifier().isSuper() &&
+            node.selector.asIdentifier() !== null);
+  }
+
+  static bool isConstructorRedirect(Send node) {
+    return (node.receiver === null &&
+            node.selector.asIdentifier() !== null &&
+            node.selector.asIdentifier().isThis()) ||
+           (node.receiver !== null &&
+            node.receiver.asIdentifier() !== null &&
+            node.receiver.asIdentifier().isThis() &&
+            node.selector.asIdentifier() !== null);
+  }
+}