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

pkg/intl/test/bidi_utils_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 bidi_utils_test;
 
 import '../lib/intl.dart';
-import '../../../pkg/unittest/unittest.dart';
+import '../../../pkg/unittest/lib/unittest.dart';
 
 /**
  * Tests the bidi utilities library.
  */
 main() {
   var LRE = '\u202A';
   var RLE = '\u202B';
   var PDF = '\u202C';
   var LRM = '\u200E';
   var RLM = '\u200F';
@@ skipping 318 matching lines @@
   });
 }
 
 class SampleItem {
   String text;
   bool isRtl;
   bool isHtml;
   SampleItem([someText='', someIsRtl=false, isHtml=false]) :
       this.text=someText, this.isRtl=someIsRtl, this.isHtml=isHtml;
 }