Move unittest from lib to pkg.

tests/html/indexeddb_3_test.dart

 #library('IndexedDB3Test');
-#import('../../lib/unittest/unittest.dart');
-#import('../../lib/unittest/html_config.dart');
+#import('../../pkg/unittest/unittest.dart');
+#import('../../pkg/unittest/html_config.dart');
 #import('dart:html');
 
 // Read with cursor.
 
 final String DB_NAME = 'Test';
 final String STORE_NAME = 'TEST';
 final String VERSION = '1';
 
 class Test {
   var db;
@@ skipping 99 matching lines @@
 }
 
 main() {
   useHtmlConfiguration();
 
   var test_ = new Test();
   test('prepare', test_.start);
   test('readAll1', test_.readAllViaCursor);
   test('readAll2', test_.readAllReversedViaCursor);
 }