Don't list pkg/third_party when finding packages

tools/testing/dart/test_suite.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.
 
 /**
  * Classes and methods for enumerating and preparing tests.
  *
  * This library includes:
  *
  * - Creating tests by listing all the Dart files in certain directories,
@@ skipping 405 matching lines @@
      */
 
     // Directories containing "-" are not valid pub packages and we therefore
     // do not include them in the list of packages.
     isValid(packageName) =>
         packageName != 'third_party' && !packageName.contains('-');
 
     var dartDir = TestUtils.dartDir;
     var futures = [
       listDir(dartDir.append('pkg'), isValid),
-      listDir(dartDir.append('pkg').append('third_party'), isValid),
       listDir(dartDir.append('third_party').append('pkg'), isValid),
       listDir(dartDir.append('runtime').append('observatory'), isValid),
     ];
     return Future.wait(futures).then((results) {
       var packageDirectories = {};
       for (var result in results) {
         for (var packageTuple in result) {
           String packageName = packageTuple[0];
           String fullPath = packageTuple[1];
           String yamlFile =
@@ skipping 1961 matching lines @@
       for (var key in PATH_REPLACEMENTS.keys) {
         if (path.startsWith(key)) {
           path = path.replaceFirst(key, PATH_REPLACEMENTS[key]);
           break;
         }
       }
     }
     return path;
   }
 }