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

test/mjsunit/compiler/osr-function.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 foo() {
   var sum = 0;
   for (var i = 0; i < 100000; i++) {
     sum += i;
   }
   return function() { return sum; }
 }
 
 assertEquals(4999950000, foo()());
 assertEquals(4999950000, foo()());
 assertEquals(4999950000, foo()());
 
 function bar() {
   var sum = 0;
   var ret = 0;
   for (var i = 0; i < 90000; i++) {
     sum += i;
     if (i == 0) ret = function() { return sum; }
   }
   return ret;
 }
 
 assertEquals(4049955000, bar()());
 assertEquals(4049955000, bar()());
 assertEquals(4049955000, bar()());