[turbofan] Remove deprecated --turbo-osr flag.

test/mjsunit/compiler/osr-function-id2.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: --use-osr --turbo-osr
+// Flags: --use-osr
 
 function id(f) { return f; }
 
 var x = (function foo() {
   var sum = 0;
   var r = id(foo);
   for (var i = 0; i < 100000; i++) {
     sum += i;
   }
   return foo == r;
 })();
 
 assertEquals(true, x);
 
 var x = (function bar() {
   var sum = 0;
   for (var i = 0; i < 90000; i++) {
     sum += i;
   }
   return bar;
 })();
 
 assertEquals("function", typeof x);