update setAnalysisRoots to accept package spec file

pkg/analysis_server/test/integration/integration_test_methods.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.
 //
 // This file has been automatically generated.  Please do not edit it manually.
 // To regenerate the file, use the script
 // "pkg/analysis_server/tool/spec/generate_files".
 
 /**
  * Convenience methods for running integration tests
@@ skipping 411 matching lines @@
    *
    *   A list of the files and directories that should be analyzed.
    *
    * excluded ( List<FilePath> )
    *
    *   A list of the files and directories within the included directories that
    *   should not be analyzed.
    *
    * packageRoots ( optional Map<FilePath, FilePath> )
    *
-   *   A mapping from source directories to target directories that should
-   *   override the normal package: URI resolution mechanism. The analyzer will
-   *   behave as though each source directory in the map contains a special
+   *   A mapping from source directories to package roots that should override
+   *   the normal package: URI resolution mechanism.
+   *
+   *   If a package root is a directory, then the analyzer will behave as
+   *   though the associated source directory in the map contains a special
    *   pubspec.yaml file which resolves any package: URI to the corresponding
-   *   path within the target directory. The effect is the same as specifying
-   *   the target directory as a "--package_root" parameter to the Dart VM when
-   *   executing any Dart file inside the source directory.
+   *   path within that package root directory. The effect is the same as
+   *   specifying the package root directory as a "--package_root" parameter to
+   *   the Dart VM when executing any Dart file inside the source directory.
+   *
+   *   If a package root is a file, then the analyzer will behave as though
+   *   that file is a ".packages" file in the source directory. The effect is
+   *   the same as specifying the file as a "--packages" parameter to the Dart
+   *   VM when executing any Dart file inside the source directory.
    *
    *   Files in any directories that are not overridden by this mapping have
    *   their package: URI's resolved using the normal pubspec.yaml mechanism.
    *   If this field is absent, or the empty map is specified, that indicates
    *   that the normal pubspec.yaml mechanism should always be used.
    */
   Future sendAnalysisSetAnalysisRoots(List<String> included, List<String> excluded, {Map<String, String> packageRoots}) {
     var params = new AnalysisSetAnalysisRootsParams(included, excluded, packageRoots: packageRoots).toJson();
     return server.send("analysis.setAnalysisRoots", params)
         .then((result) {
@@ skipping 1346 matching lines @@
       case "execution.launchData":
         expect(params, isExecutionLaunchDataParams);
         _onExecutionLaunchData.add(new ExecutionLaunchDataParams.fromJson(decoder, 'params', params));
         break;
       default:
         fail('Unexpected notification: $event');
         break;
     }
   }
 }