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

test/mjsunit/compiler/osr-labeled.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
+// Flags: --allow-natives-syntax --use-osr
 
 function foo() {
   var sum = 0;
   A: for (var i = 0; i < 5; i++) {
     B: for (var j = 0; j < 5; j++) {
       C: for (var k = 0; k < 10; k++) {
         if (k === 5) %OptimizeOsr();
         if (k === 6) break B;
         sum++;
       }
@@ skipping 22 matching lines @@
 }
 
 assertEquals(1, bar(1));
 assertEquals(1, bar(1));
 
 assertEquals(5, bar(2));
 assertEquals(5, bar(2));
 
 assertEquals(25, bar(3));
 assertEquals(25, bar(3));