Move unittest from lib to pkg.

tests/html/indexeddb_2_test.dart

 #library('IndexedDB1Test');
-#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');
 #import('dart:coreimpl');
 #import('utils.dart');
 
 // Write and re-read Maps: simple Maps; Maps with DAGs; Maps with cycles.
 
 final String DB_NAME = 'Test';
 final String STORE_NAME = 'TEST';
 final String VERSION = '1';
 
@@ skipping 77 matching lines @@
   test('test_DAG', testReadWrite(123, obj2, verifyGraph));
   test('test_cycle', testReadWrite(123, obj3, verifyGraph));
   test('test_simple_splay', testReadWrite(123, obj4, verifyGraph));
 }
 
 main() {
   useHtmlConfiguration();
 
   tests_dynamic();
 }