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

tests/html/indexeddb_4_test.dart

-#library('IndexedDB4Test');
-#import('../../pkg/unittest/unittest.dart');
-#import('../../pkg/unittest/html_config.dart');
-#import('dart:html');
+library IndexedDB4Test;
+import '../../pkg/unittest/lib/unittest.dart';
+import '../../pkg/unittest/lib/html_config.dart';
+import 'dart:html';
 
 // Test for IDBKeyRange and IDBCursor.
 
 const String DB_NAME = 'Test';
 const String STORE_NAME = 'TEST';
 const int VERSION = 1;
 
 class Test {
   fail(message) => (e) {
     guardAsync(() {
@@ skipping 156 matching lines @@
   test('upper1', test_.upper1);
   test('upper2', test_.upper2);
   test('upper3', test_.upper3);
 
   test('bound1', test_.bound1);
   test('bound2', test_.bound2);
   test('bound3', test_.bound3);
   test('bound4', test_.bound4);
   test('bound5', test_.bound5);
 }