[turbofan] Gracefully bail out if OSR encounters a loop too deeply nested.

test/mjsunit/compiler/osr-nested2.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.
+
+// Flags: --allow-natives-syntax --use-osr --turbo-osr
+
+function f() {
+  var sum = 0;
+  for (var i = 5; i < 6; i++) {
+    for (var j = 0; j < 1000000; j++) {
+      var x = i + 2;
+      var y = x + 5;
+      var z = y + 3;
+      sum += z;
+    }
+    if (true) break;
+  }
+  return sum;
+}
+
+
+assertEquals(15000000, f());
+assertEquals(15000000, f());
+assertEquals(15000000, f());