Revert "Revert "Upgrade to 5.0.71.48"" DO NOT MERGE

This reverts commit f2e3994fa5148cc3d9946666f0b0596290192b0e,
and updates the x64 makefile properly so it doesn't break that
build.

FPIIM-449

Change-Id: Ib83e35bfbae6af627451c926a9650ec57c045605
(cherry picked from commit 109988c7ccb6f3fd1a58574fa3dfb88beaef6632)
diff --git a/test/mjsunit/regress/regress-v8-4972.js b/test/mjsunit/regress/regress-v8-4972.js
new file mode 100644
index 0000000..689ae03
--- /dev/null
+++ b/test/mjsunit/regress/regress-v8-4972.js
@@ -0,0 +1,5 @@
+// Copyright 2016 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.
+
+new class extends new Proxy(class {},{}) {}