Revert of Merged: [turbofan] Fix typing rule for Math.sign.

test/mjsunit/compiler/regress-math-sign-nan-type.js

Index: test/mjsunit/compiler/regress-math-sign-nan-type.js
diff --git a/test/mjsunit/compiler/regress-math-sign-nan-type.js b/test/mjsunit/compiler/regress-math-sign-nan-type.js
deleted file mode 100644
index e16eba8c5a3b8ca48f8a055579f6f42289f40a41..0000000000000000000000000000000000000000
--- a/test/mjsunit/compiler/regress-math-sign-nan-type.js
+++ /dev/null
@@ -1,14 +0,0 @@
-// 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.
-
-// Flags: --allow-natives-syntax
-
-function f(a) {
-  return Math.sign(+a) < 2;
-}
-
-f(NaN);
-f(NaN);
-%OptimizeFunctionOnNextCall(f);
-assertFalse(f(NaN));