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;  // Variable shadows function name.
+   assertEquals("undefined", typeof f);
+})();
+
+(function f(){
+   var f;
+   assertEquals("undefined", typeof f);
+   with ({});  // Force context allocation of both variable and function name.
+})();
+
+assertEquals("undefined", typeof f);
+
+// var initialization is intercepted by with scope.
+(function() {
+  var o = { a: 1 };
+  with (o) {
+    var a = 2;
+  }
+  assertEquals("undefined", typeof a);
+  assertEquals(2, o.a);
+})();
+
+// const initialization is not intercepted by with scope.
+(function() {
+  var o = { a: 1 };
+  with (o) {
+    const a = 2;
+  }
+  assertEquals(2, a);
+  assertEquals(1, o.a);
+})();