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

pkg/unittest/lib/html_layout_config.dart

Index: pkg/unittest/lib/html_layout_config.dart
===================================================================
--- pkg/unittest/lib/html_layout_config.dart	(revision 0)
+++ pkg/unittest/lib/html_layout_config.dart	(working copy)
@@ -9,11 +9,11 @@
  * recreated the IFrame for each test, here the IFrames are preserved.
  * Furthermore we post a message on completion.
  */
-#library('html_layout_config');
+library html_layout_config;
 
-#import('dart:html');
-#import('dart:math');
-#import('unittest.dart');
+import 'dart:html';
+import 'dart:math';
+import 'unittest.dart';
 
 /** The messages exchanged between parent and child. */
 // TODO(gram) At some point postMessage was supposed to support