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

test/mjsunit/compiler/try-osr.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 --turbo-osr
+// Flags: --allow-natives-syntax
 
 function OSRInsideTry(x) {
   try {
     for (var i = 0; i < 10; i++) { if (i == 5) %OptimizeOsr(); }
     throw x;
   } catch (e) {
     return e + 1;
   }
   return x + 2;
 }
@@ skipping 26 matching lines @@
 
 function OSRInsideFinally_ReThrow(x) {
   try {
     throw x;
   } finally {
     for (var i = 0; i < 10; i++) { if (i == 5) %OptimizeOsr(); }
   }
   return x + 2;
 }
 assertThrows("OSRInsideFinally_ReThrow(new Error)", Error);