[x64] Fix handling of Smi constants in LSubI and LBitI

test/mjsunit/regress/regress-crbug-478612.js

+// Copyright 2015 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
+
+// This is used to force binary operations below to have tagged representation.
+var z = {valueOf: function() { return 3; }};
+
+
+function f() {
+  var y = -2;
+  return (1 & z) - y++;
+}
+
+assertEquals(3, f());
+assertEquals(3, f());
+%OptimizeFunctionOnNextCall(f);
+assertEquals(3, f());
+
+
+function g() {
+  var y = 2;
+  return (1 & z) | y++;
+}
+
+assertEquals(3, g());
+assertEquals(3, g());
+%OptimizeFunctionOnNextCall(g);
+assertEquals(3, g());
+
+
+function h() {
+  var y = 3;
+  return (3 & z) & y++;
+}
+
+assertEquals(3, h());
+assertEquals(3, h());
+%OptimizeFunctionOnNextCall(h);
+assertEquals(3, h());
+
+
+function i() {
+  var y = 2;
+  return (1 & z) ^ y++;
+}
+
+assertEquals(3, i());
+assertEquals(3, i());
+%OptimizeFunctionOnNextCall(i);
+assertEquals(3, i());