Revert of [parsing] Fix maybe-assigned for loop variables.

test/mjsunit/regress/regress-5636-2.js

-// 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(n) {
-  "use asm";
-  var a = [];
-  function g() { return x }
-  for (var i = 0; i < n; ++i) {
-    var x = i;
-    a[i] = g;
-    %OptimizeFunctionOnNextCall(g);
-    g();
-  }
-  return a;
-}
-var a = f(3);
-assertEquals(3, a.length);
-assertEquals(2, a[0]());
-assertEquals(2, a[1]());
-assertEquals(2, a[2]());