Unify dart:async and pub/io.dart TimeoutException classes.

sdk/lib/_internal/pub/lib/src/command/uploader.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 pub.command.uploader;
 
-import 'dart:async' hide TimeoutException;
+import 'dart:async';
 
 import 'package:path/path.dart' as path;
 
 import '../command.dart';
 import '../entrypoint.dart';
 import '../exit_codes.dart' as exit_codes;
 import '../http.dart';
 import '../io.dart';
 import '../log.dart' as log;
 import '../oauth2.dart' as oauth2;
@@ skipping 57 matching lines @@
               "${Uri.encodeComponent(package)}/uploaders/"
               "${Uri.encodeComponent(uploader)}");
           return client.delete(url, headers: PUB_API_HEADERS);
         }
       });
     }).then(handleJsonSuccess)
       .catchError((error) => handleJsonError(error.response),
                   test: (e) => e is PubHttpException);
   }
 }