Fix build for throwsStateError: remove duplicate definitions in other tests.

pkg/oauth2/test/utils.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.
 
 library utils;
 
 import 'dart:async';
 import 'dart:collection' show Queue;
 
 import '../../unittest/lib/unittest.dart';
@@ skipping 27 matching lines @@
 
   Future<http.Response> _handleRequest(http.Request request) {
     if (_handlers.isEmpty) {
       return new Future.immediate(new http.Response('not found', 404));
     } else {
       return _handlers.removeFirst()(request);
     }
   }
 }
 
-// TODO(nweiz): remove this once it's built in to unittest
-/// A matcher for StateErrors.
-const isStateError = const _StateError();
-
-/// A matcher for functions that throw StateError.
-const Matcher throwsStateError =
-    const Throws(isStateError);
-
-class _StateError extends TypeMatcher {
-  const _StateError() : super("StateError");
-  bool matches(item, MatchState matchState) => item is StateError;
-}
-
 /// A matcher for AuthorizationExceptions.
 const isAuthorizationException = const _AuthorizationException();
 
 /// A matcher for functions that throw AuthorizationException.
 const Matcher throwsAuthorizationException =
     const Throws(isAuthorizationException);
 
 class _AuthorizationException extends TypeMatcher {
   const _AuthorizationException() : super("AuthorizationException");
   bool matches(item, MatchState matchState) =>
     item is oauth2.AuthorizationException;
 }
 
 /// A matcher for ExpirationExceptions.
 const isExpirationException = const _ExpirationException();
 
 /// A matcher for functions that throw ExpirationException.
 const Matcher throwsExpirationException =
     const Throws(isExpirationException);
 
 class _ExpirationException extends TypeMatcher {
   const _ExpirationException() : super("ExpirationException");
   bool matches(item, MatchState matchState) =>
     item is oauth2.ExpirationException;
 }