[turbofan] Fix typing rule for JSCreateArguments.

test/mjsunit/regress/regress-crbug-712802.js

Index: test/mjsunit/regress/regress-crbug-712802.js
diff --git a/test/mjsunit/regress/regress-crbug-712802.js b/test/mjsunit/regress/regress-crbug-712802.js
new file mode 100644
index 0000000000000000000000000000000000000000..e23519e179bbd911754771ca55da1fe0957b3cef
--- /dev/null
+++ b/test/mjsunit/regress/regress-crbug-712802.js
@@ -0,0 +1,12 @@
+// Copyright 2017 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
+
+function foo(...args) { return Array.isArray(args); }
+
+assertTrue(foo());
+assertTrue(foo());
+%OptimizeFunctionOnNextCall(foo);
+assertTrue(foo());