Correct file names for tests in tests/language.

tests/language/exception_in_increment.dart

-// Copyright (c) 2012, 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.
-// Test throws exception in the middle of the increment operation, the setter
-// part of the instance field increment never completes.
-
-main() {
-  var a = new A();
-  a.field = new A();
-  for (int i = 0; i < 4000; i++) {
-    try {
-      a.foo(i);
-    } catch (e) {
-      // Ignore.
-    }
-  }
-}
-
-class A {
-  var field;
-  foo(i) {
-    field++;  // throw exception
-  }
-}