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

test/mjsunit/regress/regress-crbug-480807.js

Index: test/mjsunit/regress/regress-crbug-480807.js
diff --git a/test/mjsunit/regress/regress-crbug-480807.js b/test/mjsunit/regress/regress-crbug-480807.js
index c273f20a78bfeb4c7b48cdb2b5fb12fc9d78b5e7..a1448d6de655fdec10dd4442527e8711ad5b6ada 100644
--- a/test/mjsunit/regress/regress-crbug-480807.js
+++ b/test/mjsunit/regress/regress-crbug-480807.js
@@ -2,7 +2,7 @@
 // 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 --noalways-opt
+// Flags: --allow-natives-syntax --use-osr --noalways-opt
 
 function foo() {
   var c = 0;