[turbofan] Fix control reducer bug with walking non-control edges during ConnectNTL phase.

test/mjsunit/regress/regress-469605.js

+// Copyright 2015 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 counter() {
+  var i = 100;
+  return function() {
+    if (i-- > 0) return i;
+    throw "done";
+  }
+}
+
+var c1 = counter();
+var c2 = counter();
+
+var f = (function() {
+  "use asm";
+  return function f(i) {
+    i = i|0;
+    do {
+      if (i > 0) c1();
+      else c2();
+    } while (true);
+  }
+})();
+
+assertThrows(function() { f(0); });
+assertThrows(function() { f(1); });
+
+var c3 = counter();
+
+var g = (function() {
+  "use asm";
+  return function g(i) {
+    i = i + 1;
+    do {
+      i = c3(i);
+    } while (true);
+  }
+})();
+
+assertThrows(function() { g(0); });
+assertThrows(function() { g(1); });