Update utils to new library syntax.

utils/css/tool.dart

 // Copyright (c) 2011, 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('csstool');
+library csstool;
 
-#import('dart:io');
-#import('css.dart');
-#import('../lib/file_system.dart');
-#import('../lib/file_system_vm.dart');
+import 'dart:io';
+import 'css.dart';
+import '../lib/file_system.dart';
+import '../lib/file_system_vm.dart';
 
 
 FileSystem files;
 
 /** Invokes [callback] and returns how long it took to execute in ms. */
 num time(callback()) {
   final watch = new Stopwatch();
   watch.start();
   callback();
   watch.stop();
@@ skipping 55 matching lines @@
 
     files.writeString(outputFullFn, buff.toString());
     print("Generated file ${outputFullFn}");
 
     // Generate CSS.dart file.
     String genDartClassFile = Generate.dartClass(files, outPath, stylesheet,
         sourceFilename);
     print("Generated file ${genDartClassFile}");
   }
 }