Update charted to 0.4.8 and roll

packages/usage/tool/grind.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.
 
 library usage.grind;
 
 import 'dart:io';
 
 import 'package:grinder/grinder.dart';
 
 final Directory _buildExampleDir = new Directory('build/example');
 
 main(List<String> args) => grind(args);
 
-@Task('Do any necessary build set up')
-void init() {
-  // Verify we're running in the project root.
-  if (!getDir('lib').existsSync() || !getFile('pubspec.yaml').existsSync()) {
-    context.fail('This script must be run from the project root.');
-  }
-
-  _buildExampleDir.createSync(recursive: true);
-}
+@Task()
+void init() => _buildExampleDir.createSync(recursive: true);
 
 @Task()
 @Depends(init)
 void build() {
   // Compile `test/web_test.dart` to the `build/test` dir; measure its size.
   File srcFile = new File('example/example.dart');
-  Dart2js.compile(srcFile, outDir: _buildExampleDir, minify: true);
+  Dart2js.compile(srcFile,
+      outDir: _buildExampleDir,
+      minify: true,
+      extraArgs: ['--conditional-directives']);
   File outFile = joinFile(_buildExampleDir, ['example.dart.js']);
 
-  context.log('${outFile.path} compiled to ${_printSize(outFile)}');
+  log('${outFile.path} compiled to ${_printSize(outFile)}');
 }
 
-@Task('Delete all generated artifacts')
-void clean() {
-  // Delete the build/ dir.
-  delete(buildDir);
-}
+@Task()
+void clean() => delete(buildDir);
 
 String _printSize(File file) => '${(file.lengthSync() + 1023) ~/ 1024}k';