Fix assignment of function name constant.

test/mjsunit/regress/regress-3138.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.
+
+(function f(){
+   assertEquals("function", typeof f);
+})();
+
+(function f(){
+   var f;
+   assertEquals("undefined", typeof f);
+})();
+
+(function f(){
+   var f;
+   assertEquals("undefined", typeof f);
+   with ({});
+})();
+
+assertEquals("undefined", typeof f);
+
+(function() {
+  with ( {} ) const a = 3;

[rossberg, 2014/02/14 11:56:21]

How exactly is this test related?

Can we either remove it, or at least change it so that it is compatible with
upcoming ES6 semantics?

+  assertEquals(3, a);
+})();