Fix argument expectation Runtime_StringParseInt.

test/mjsunit/regress/regress-parseint.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
+
+function f(string, radix) {
+  // Use a phi to force radix into heap number representation.
+  radix = (radix == 0) ? radix : (radix >> 0);
+  if (radix != 2) return NaN;
+  return %StringParseInt(string, radix);
+}
+
+assertEquals(2, (-4294967294) >> 0);
+assertEquals(3, f("11", -4294967294));
+assertEquals(NaN, f("11", -2147483650));
+%OptimizeFunctionOnNextCall(f);
+assertEquals(3, f("11", -4294967294));