fixes #610, incorrect help output

test/codegen_test.dart

 // Copyright (c) 2016, 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.
 
 /// Tests code generation.
 ///
 /// Runs Dart Dev Compiler on all input in the `codegen` directory and checks
 /// that the output is what we expected.
 library dev_compiler.test.codegen_test;
 
@@ skipping 76 matching lines @@
     path.join('lib', 'math'),
     path.join('lib', 'typed_data'),
   ];
 
   // Copy all of the test files and expanded multitest files to
   // gen/codegen_tests. We'll compile from there.
   var testFiles = _setUpTests(testDirs);
 
   // Our default compiler options. Individual tests can override these.
   var defaultOptions = ['--no-source-map', '--no-summarize'];
-  var compilerArgParser = CompilerOptions.addArguments(new ArgParser());
+  var compilerArgParser = new ArgParser();
+  CompilerOptions.addArguments(compilerArgParser);
 
   // Compile each test file to JS and put the result in gen/codegen_output.
   for (var testFile in testFiles) {
     var relativePath = path.relative(testFile, from: codegenTestDir);
 
     // Only compile the top-level files for generating coverage.
     if (codeCoverage && path.dirname(relativePath) != ".") continue;
 
     var name = path.withoutExtension(relativePath);
     test('dartdevc $name', () {
@@ skipping 232 matching lines @@
 /// Simplified from ParseDartTask.resolveDirective.
 String _resolveDirective(UriBasedDirective directive) {
   StringLiteral uriLiteral = directive.uri;
   String uriContent = uriLiteral.stringValue;
   if (uriContent != null) {
     uriContent = uriContent.trim();
     directive.uriContent = uriContent;
   }
   return directive.validate() == null ? uriContent : null;
 }