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

pkg/unittest/lib/description.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.
 /**
  * The default implementation of IDescription. This should rarely need
  * substitution, although conceivably it is a place where other languages
  * could be supported.
  */
 
-part of unittest;
+part of matcher;
 
 class StringDescription implements Description {
   var _out;
 
   /** Initialize the description with initial contents [init]. */
   StringDescription([String init = '']) {
     _out = init;
   }
 
   /** Get the description as a string. */
@@ skipping 71 matching lines @@
     else if (ch == '\n')
       return '\\n';
     else if (ch == '\r')
       return '\\r';
     else if (ch == '\t')
       return '\\t';
     else
       return ch;
   }
 }