[turbofan] Fix control reducer bug with NTLs.

test/mjsunit/regress-ntl.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 mod1() {
+  var v_1 = 1;
+  var v_2 = 1;
+  v_1++;
+  v_2 = {valueOf: function() { throw "gagh"; }};
+
+  function bug1() {
+    for (var i = 0; i < 1; v_2++) {
+      if (v_1 == 1) ;
+    }
+  }
+
+  return bug1;
+}
+
+var f = mod1();
+assertThrows(f);
+%OptimizeFunctionOnNextCall(f);
+assertThrows(f);
+
+
+var v_3 = 1;
+var v_4 = 1;
+v_3++;
+v_4 = {valueOf: function() { throw "gagh"; }};
+
+function bug2() {
+  for (var i = 0; i < 1; v_4++) {
+    if (v_3 == 1) ;
+  }
+}
+
+assertThrows(bug2);
+%OptimizeFunctionOnNextCall(bug2);
+assertThrows(bug2);