Add --x-perf-report flag to the dartanalyzer command

pkg/analyzer_cli/lib/src/options.dart

 // Copyright (c) 2015, 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 analyzer_cli.src.options;
 
 import 'dart:io';
 
 import 'package:analyzer_cli/src/driver.dart';
 import 'package:args/args.dart';
@@ skipping 62 matching lines @@
 
   /// Whether to use machine format for error display
   final bool machineFormat;
 
   /// The path to the package root
   final String packageRootPath;
 
   /// The path to a `.packages` configuration file
   final String packageConfigPath;
 
+  /// The path to a file to write a performance log.
+  /// (Or null if not enabled.)
+  final String perfReport;
+
   /// Batch mode (for unit testing)
   final bool shouldBatch;
 
   /// Whether to show package: warnings
   final bool showPackageWarnings;
 
   /// Whether to show SDK warnings
   final bool showSdkWarnings;
 
   /// The source files to analyze
@@ skipping 17 matching lines @@
         enableStrictCallChecks = args['enable-strict-call-checks'],
         enableSuperMixins = args['supermixin'],
         enableTypeChecks = args['enable_type_checks'],
         hintsAreFatal = args['fatal-hints'],
         ignoreUnrecognizedFlags = args['ignore-unrecognized-flags'],
         lints = args['lints'],
         log = args['log'],
         machineFormat = args['machine'] || args['format'] == 'machine',
         packageConfigPath = args['packages'],
         packageRootPath = args['package-root'],
+        perfReport = args['x-perf-report'],
         shouldBatch = args['batch'],
         showPackageWarnings =
             args['show-package-warnings'] || args['package-warnings'],
         showSdkWarnings = args['show-sdk-warnings'] || args['warnings'],
         sourceFiles = args.rest,
         warningsAreFatal = args['fatal-warnings'],
         strongMode = args['strong'];
 
   /// Parse [args] into [CommandLineOptions] describing the specified
   /// analyzer options. In case of a format error, calls [printAndFail], which
@@ skipping 111 matching lines @@
           defaultsTo: false,
           negatable: false)
       ..addFlag('warnings',
           help: 'Show warnings from SDK imports.',
           defaultsTo: false,
           negatable: false)
       ..addFlag('show-sdk-warnings',
           help: 'Show warnings from SDK imports (deprecated).',
           defaultsTo: false,
           negatable: false)
+      ..addOption('x-perf-report',
+          help: 'Writes a performance report to the given file (experimental).')
       ..addFlag('help',
           abbr: 'h',
           help: 'Display this help message.',
           defaultsTo: false,
           negatable: false)
       ..addOption('url-mapping',
           help: '--url-mapping=libraryUri,/path/to/library.dart directs the '
               'analyzer to use "library.dart" as the source for an import '
               'of "libraryUri".',
           allowMultiple: true,
@@ skipping 226 matching lines @@
 
   int _getNextFlagIndex(args, i) {
     for (; i < args.length; ++i) {
       if (args[i].startsWith('--')) {
         return i;
       }
     }
     return i;
   }
 }