Setup getter and setter elements.

dart/frog/leg/frog_leg.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.
 
 #library('frog_leg');
 
 #import('../lang.dart', prefix: 'frog');
 #import('elements/elements.dart');
 #import('io/io.dart', prefix: 'io');
 #import('leg.dart');
@@ skipping 73 matching lines @@
   }
 
   Script readScript(String filename) {
     String text = frog.world.files.readAll(filename);
     frog.SourceFile sourceFile = new frog.SourceFile(filename, text);
     return new Script(sourceFile);
   }
 
   String get legDirectory() => io.join([frog.options.libDir, '..', 'leg']);
 
-  void cancel([String reason, Node node, token, instruction]) {
+  void cancel([String reason, Node node, token, instruction, element]) {
     Script script = currentScript();
     if (node !== null) {
       print(spanFromNode(node, script).toMessageString("cancel leg: $reason"));
     } else if (token !== null) {
       String tokenString = token.toString();
       int begin = token.charOffset;
       int end = begin + tokenString.length;
       print(script.file.getLocationMessage("cancel leg: $reason",
                                            begin, end, true));
+    } else if (element !== null) {
+      currentElement = element;
+      cancel(reason: reason, token: element.position());
     }
     if (throwOnError) {
       throw new AbortLeg(reason);
     }
     super.cancel(reason, node, token, instruction);
   }
 }
 
 class AbortLeg {
   final message;
   AbortLeg(this.message);
   toString() => 'Aborted due to --throw-on-error: $message';
 }