Restructure pkg/unittest and pkg/webdriver to follow the pub conventions.

tests/isolate/timer_cancel2_test.dart

 // Copyright (c) 2012, 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('timer_cancel2_test');
+library timer_cancel2_test;
 
-#import("dart:isolate");
-#import('../../pkg/unittest/unittest.dart');
+import 'dart:isolate';
+import '../../pkg/unittest/lib/unittest.dart';
 
 main() {
   // Test that a timeout handler can cancel itself.
   test("timer cancel test 2", () {
     var cancelTimer;
 
     void cancelHandler(Timer timer) {
       cancelTimer.cancel();
     }
 
     cancelTimer = new Timer.repeating(1, expectAsync1(cancelHandler));
   });
 }