Throw CyclicInitializationError instead of string

runtime/lib/errors_patch.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.
 
 patch class Error {
   /* patch */ static String _objectToString(Object object) {
     return Object._toString(object);
   }
 
   /* patch */ StackTrace get stackTrace => _stackTrace;
@@ skipping 92 matching lines @@
   String _url;
   int _line;
 }
 
 class _InternalError {
   const _InternalError(this._msg);
   String toString() => "InternalError: '${_msg}'";
   final String _msg;
 }
 
+patch class CyclicInitializationError {
+  static _throwNew(String variableName) {
+    throw new CyclicInitializationError(variableName);
+  }
+}
 
 patch class AbstractClassInstantiationError {
   AbstractClassInstantiationError._create(
       this._className, this._url, this._line);
 
   static _throwNew(int case_clause_pos, String className)
       native "AbstractClassInstantiationError_throwNew";
 
   /* patch */ String toString() {
     return "Cannot instantiate abstract class $_className: "
@@ skipping 191 matching lines @@
     return msg_buf.toString();
   }
 }
 
 class _JavascriptIntegerOverflowError extends Error {
   final Object _value;
 
   _JavascriptIntegerOverflowError(this._value);
   String toString() => "Javascript Integer Overflow: $_value";
 }