Migrate the language tests up to arithmetic_test.

tests/language/accessor_conflict_import_prefixed2_test.dart

Index: tests/language/accessor_conflict_import_prefixed2_test.dart
diff --git a/tests/language/accessor_conflict_import_prefixed2_test.dart b/tests/language/accessor_conflict_import_prefixed2_test.dart
deleted file mode 100644
index 88ab758cdb679d652e884e32dd2b310304683dc8..0000000000000000000000000000000000000000
--- a/tests/language/accessor_conflict_import_prefixed2_test.dart
+++ /dev/null
@@ -1,18 +0,0 @@
-// Copyright (c) 2016, 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.
-
-// Verify that a getter and its corresponding setter can be imported from two
-// different files.  In this test the setter is imported first.
-
-import "package:expect/expect.dart";
-
-import "accessor_conflict_setter.dart" as p;
-import "accessor_conflict_getter.dart" as p;
-
-main() {
-  p.getValue = 123;
-  Expect.equals(p.x, 123);
-  p.x = 456;
-  Expect.equals(p.setValue, 456);
-}