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

tests/html/window_nosuchmethod_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('WindowNSMETest');
-#import('../../pkg/unittest/unittest.dart');
-#import('../../pkg/unittest/html_config.dart');
-#import('dart:html', prefix: 'dom');
+library WindowNSMETest;
+import '../../pkg/unittest/lib/unittest.dart';
+import '../../pkg/unittest/lib/html_config.dart';
+import 'dart:html' as dom;
 
 // Not defined in dom.Window.
 foo(x) => x;
 
 class Unused {
   foo(x) => 'not $x';
 }
 
 int inscrutable(int x) => x == 0 ? 0 : x | inscrutable(x & (x - 1));
 
@@ skipping 26 matching lines @@
       try {
         String x = dom.window.foo(message);
         expect(false, isTrue, reason: 'Should not reach here: $x');
       } on NoSuchMethodError catch (e) {
         // Expected exception.
       } on Exception catch (e) {
         expect(false, isTrue, reason: 'Wrong exception: $e');
       }
     });
 }