pkg/scheduled_test: fix analyzer hints

test/descriptor/pattern_test.dart

 // Copyright (c) 2013, 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.
 
 import 'package:scheduled_test/descriptor.dart' as d;
 import 'package:scheduled_test/scheduled_test.dart';
 
-import 'package:metatest/metatest.dart';
 import 'utils.dart';
 
 String sandbox;
 
 void main() {
   expectTestPasses("pattern().validate() succeeds if there's a file matching "
       "the pattern and the child entry", () {
     scheduleSandbox();
 
     d.file('foo', 'blap').create();
@@ skipping 85 matching lines @@
     d.filePattern(new RegExp(r'f..'), 'bar').validate();
   }, (error) {
     expect(error.toString(), matches(
         r"^Multiple valid entries found in '[^']+' matching "
         r"\/f\.\./:\n"
         r"\* faa\n"
         r"\* fee\n"
         r"\* foo$"));
   });
 }