test rename overhaul: step 8 - language tests

tests/language/string_unicode3_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.
 
 class StringUnicode3NegativeTest {
 
   static testMain() {
     // (backslash) xXX must have exactly 2 hex digits
     String str = "Foo\x0";
     str = "Foo\xF Bar";
   }
 }
 
 main() {
   StringUnicode3NegativeTest.testMain();
 }