Rename "pathos" package to "path".

sdk/lib/_internal/pub/test/validator/lib_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:pathos/path.dart' as path;
+import 'package:path/path.dart' as path;
 import 'package:scheduled_test/scheduled_test.dart';
 
 import '../../lib/src/entrypoint.dart';
 import '../../lib/src/io.dart';
 import '../../lib/src/validator.dart';
 import '../../lib/src/validator/lib.dart';
 import '../descriptor.dart' as d;
 import '../test_pub.dart';
 import 'utils.dart';
 
@@ skipping 37 matching lines @@
           deleteEntry(path.join(sandboxDir, appPath, "lib", "test_pkg.dart")));
       d.dir(appPath, [
         d.dir("lib", [
           d.dir("src", [d.file("test_pkg.dart", "int i = 0;")])
         ])
       ]).create();
       expectValidationError(lib);
     });
   });
 }