Make mirror_in_static_init_test a multitest

tests/language/mirror_in_static_init_test.dart

-// Copyright (c) 2015, 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.
-
-// Error in class finalization triggered via mirror in a static initializer.
-// Simply check that we do not crash.
-
-library mirror_in_static_init_test;
-
-import 'dart:mirrors';
-
-abstract class C {
-  int _a;
-  C([this._a: 0]);
-}
-
-final int staticField = () {
-  var lib = currentMirrorSystem().findLibrary(#mirror_in_static_init_test);
-  var lst = List.from(lib.declarations.values);
-  return 42;
-}();
-
-main() {
-  return staticField;
-}