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

pkg/fixnum/fixnum.dart

Index: pkg/fixnum/fixnum.dart
===================================================================
--- pkg/fixnum/fixnum.dart	(revision 14313)
+++ pkg/fixnum/fixnum.dart	(working copy)
@@ -2,8 +2,8 @@
 // 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('fixnum');
-#import('dart:math', prefix: 'Math');
-#source('intx.dart');
-#source('int32.dart');
-#source('int64.dart');
+library fixnum;
+import 'dart:math' as Math;
+part 'intx.dart';
+part 'int32.dart';
+part 'int64.dart';