[turbofan] Fix OSR entry in case label.

test/mjsunit/regress/regress-osr-in-case-label.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 --harmony-do-expressions
+
+function f(x) {
+  switch (x) {
+    case 1: return "one";
+    case 2: return "two";
+    case do { for (var i = 0; i < 10; i++) { if (i == 5) %OptimizeOsr(); } }:
+    case 3: return "WAT";
+  }
+}
+
+assertEquals("one", f(1));
+assertEquals("two", f(2));
+assertEquals("WAT", f(3));