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

tests/isolate/timer_cancel1_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_cancel1_test');
-
-#import("dart:isolate");
-#import('../../pkg/unittest/unittest.dart');
+library timer_cancel1_test;
+import 'dart:isolate';
+import '../../pkg/unittest/lib/unittest.dart';
 
 main() {
   // Test that a timeout handler can cancel another.
   test("timer cancel1 test", () {
     var canceleeTimer;
     var cancelerTimer;
 
     void unreachable(Timer timer) {
       fail("A canceled timeout handler should be unreachable.");
     }
 
     void handler(Timer timer) {
       canceleeTimer.cancel();
     }
 
     cancelerTimer = new Timer(1, expectAsync1(handler));
     canceleeTimer = new Timer(1000, expectAsync1(unreachable, count: 0));
   });
 }