Don't invoke user-defined code in NoSuchMethodError.toString.

dart/lib/core/errors.dart

 // Copyright (c) 2012, 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.
 
 class Error {
   const Error();
 }
 
 class AssertionError implements Error {
 }
@@ skipping 39 matching lines @@
                           List this._arguments,
                           [List existingArgumentNames = null])
       : this._existingArgumentNames = existingArgumentNames;
 
   String toString() {
     StringBuffer sb = new StringBuffer();
     for (int i = 0; i < _arguments.length; i++) {
       if (i > 0) {
         sb.add(", ");
       }
-      sb.add(_arguments[i]);
+      sb.add(safeToString(_arguments[i]));
     }
     if (_existingArgumentNames === null) {
       return "NoSuchMethodError : method not found: '$_functionName'\n"
-          "Receiver: $_receiver\n"
+          "Receiver: ${safeToString(_receiver)}\n"
           "Arguments: [$sb]";
     } else {
       String actualParameters = sb.toString();
       sb = new StringBuffer();
       for (int i = 0; i < _existingArgumentNames.length; i++) {
         if (i > 0) {
           sb.add(", ");
         }
         sb.add(_existingArgumentNames[i]);
       }
       String formalParameters = sb.toString();
       return "NoSuchMethodError: incorrect number of arguments passed to "
-          "method named '$_functionName'\nReceiver: $_receiver\n"
+          "method named '$_functionName'\n"
+          "Receiver: ${safeToString(_receiver)}\n"
           "Tried calling: $_functionName($actualParameters)\n"
           "Found: $_functionName($formalParameters)";
     }
   }
+
+  external static String safeToString(Object object);
 }