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

pkg/unittest/lib/numeric_matchers.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.
 
 /**
  * Returns a matcher which matches if the match argument is greater
  * than the given [value].
  */
 
-part of unittest;
+part of matcher;
 
 Matcher greaterThan(value) =>
   new _OrderingComparison(value, false, false, true, 'a value greater than');
 
 /**
  * Returns a matcher which matches if the match argument is greater
  * than or equal to the given [value].
  */
 Matcher greaterThanOrEqualTo(value) =>
   new _OrderingComparison(value, true, false, true,
@@ skipping 202 matching lines @@
       return mismatchDescription.
           addDescriptionOf(item).
           add(' not numeric');
     } else {
       return super.describeMismatch(item, mismatchDescription,
           matchState, verbose);
     }
   }
 }