Get rid of some unused "hide" declarations.

lib/src/frontend/throws_matchers.dart

 // Copyright (c) 2014, 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 test.frontend.throws_matchers;
 
-import 'package:matcher/matcher.dart' hide Throws;
+import 'package:matcher/matcher.dart';
 
 import 'throws_matcher.dart';
 
 /// A matcher for functions that throw ArgumentError.
 const Matcher throwsArgumentError = const Throws(isArgumentError);
 
 /// A matcher for functions that throw ConcurrentModificationError.
 const Matcher throwsConcurrentModificationError =
     const Throws(isConcurrentModificationError);
 
@@ skipping 17 matching lines @@
 const Matcher throwsRangeError = const Throws(isRangeError);
 
 /// A matcher for functions that throw StateError.
 const Matcher throwsStateError = const Throws(isStateError);
 
 /// A matcher for functions that throw Exception.
 const Matcher throwsUnimplementedError = const Throws(isUnimplementedError);
 
 /// A matcher for functions that throw UnsupportedError.
 const Matcher throwsUnsupportedError = const Throws(isUnsupportedError);