Update worker mode to use the bazel protos directly instead of json

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 245 matching lines @@
           Platform.script.resolve('../../version').toFilePath();
       File versionFile = new File(versionPath);
       return versionFile.readAsStringSync().trim();
     } catch (_) {
       // This happens when the script is not running in the context of an SDK.
       return "<unknown>";
     }
   }
 
   static CommandLineOptions _parse(List<String> args) {
+    // Check if the args are in a file (bazel worker mode).
+    if (args.last.startsWith('@')) {
+      var argsFile = new File(args.last.substring(1));
+      args = argsFile.readAsLinesSync();
+    }
+
     args = args.expand((String arg) => arg.split('=')).toList();
     var parser = new CommandLineParser()
       ..addFlag('batch',
           abbr: 'b',
           help: 'Read commands from standard input (for testing).',
           defaultsTo: false,
           negatable: false)
       ..addOption('dart-sdk', help: 'The path to the Dart SDK.')
       ..addOption('packages',
           help:
@@ skipping 377 matching lines @@
 
   int _getNextFlagIndex(args, i) {
     for (; i < args.length; ++i) {
       if (args[i].startsWith('--')) {
         return i;
       }
     }
     return i;
   }
 }