test rename overhaul: step 8 - language tests

tests/language/string_interpolate2_negative_test.dart

 // Copyright (c) 2011, 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.
 // Dart test program testing that the interpolated identifier starts with an
 // ident start character.
 
 class StringInterpolate2NegativeTest {
 
   static testMain() {
     var $x = 1;
     var s = "eins und $-x macht zwei.";
     print(s);
   }
 
 }
 
 main() {
   StringInterpolate2NegativeTest.testMain();
 }