Extract ElementBuilder tests into a separate file.

pkg/analyzer/test/dart/element/test_all.dart

 // Copyright (c) 2014, 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 analyzer.test.dart.element.test_all;
 
 import 'package:test_reflective_loader/test_reflective_loader.dart';
 
+import 'builder_test.dart' as builder;
 import 'element_test.dart' as element;
 
 /// Utility for manually running all tests.
 main() {
   defineReflectiveSuite(() {
+    builder.main();
     element.main();
   }, name: 'element');
 }