[turbofan] Remove deprecated --turbo-from-bytecode flag.

test/mjsunit/ignition/osr-from-bytecode.js

 // Copyright 2016 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 --ignition --ignition-osr --turbo-from-bytecode
+// Flags: --allow-natives-syntax --ignition --ignition-osr
 
 function f() {
   for (var i = 0; i < 10; i++) {
     if (i == 5) %OptimizeOsr();
   }
 }
 f();