Add test case for serializing external references to runtime functions.

R=svenpanne@chromium.org
BUG=chromium:465564
LOG=N

Review URL: https://codereview.chromium.org/996603002

Cr-Commit-Position: refs/heads/master@{#27093}

test/mjsunit/regress/regress-crbug-465564.js

+// Copyright 2014 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+// Flags: --allow-natives-syntax --cache=code
+
+assertEquals(-1, %StringCompare("a", "b"));