test rename overhaul: step 8 - language tests

tests/language/override_field_method6_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 error for overriding method with setter.
 
 class A {
   foo(x) { }
 }
 
 class B extends A {
   set foo(x) { }  // setter cannot override method.
 }
 
 class OverrideFieldMethod6NegativeTest {
   static testMain() {
     new B().foo = 10;
   }
 }
 
 main() {
   OverrideFieldMethod6NegativeTest.testMain();
 }