Split js_backend_cps_ir tests into multiple test units.

tests/compiler/dart2js/js_backend_cps_ir_literals.dart

-// Copyright (c) 2014, 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.
-
-// Tests of literals.
-
-library literals_tests;
-
-import 'js_backend_cps_ir_test.dart';
-
-const List<TestEntry> tests = const [
-  const TestEntry("""
-main() {
-  print([]);
-  print([1]);
-  print([1, 2]);
-  print([1, [1, 2]]);
-  print({});
-  print({1: 2});
-  print({[1, 2]: [3, 4]});
-}
-""",
-r"""
-function() {
-  P.print([]);
-  P.print([1]);
-  P.print([1, 2]);
-  P.print([1, [1, 2]]);
-  P.print(P.LinkedHashMap_LinkedHashMap$_empty());
-  P.print(P.LinkedHashMap_LinkedHashMap$_literal([1, 2]));
-  P.print(P.LinkedHashMap_LinkedHashMap$_literal([[1, 2], [3, 4]]));
-  return null;
-}"""),
-];