VM: Make use_osr an Isolate flag, similar to how we made use_field_guards.

runtime/vm/kernel_isolate.cc

 // Copyright (c) 2016, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "vm/kernel_isolate.h"
 
 #include "vm/compiler.h"
 #include "include/dart_native_api.h"
 #include "vm/dart_api_impl.h"
 #include "vm/dart_entry.h"
@@ skipping 53 matching lines @@
         KernelIsolate::create_callback();
 
     if (create_callback == NULL) {
       KernelIsolate::FinishedInitializing();
       return;
     }
 
     // Note: these flags must match those passed to the VM during
     // the app-jit training run (see //utils/kernel-service/BUILD.gn).
     Dart_IsolateFlags api_flags;
-    api_flags.version = DART_FLAGS_CURRENT_VERSION;
+    Isolate::FlagsInitialize(&api_flags);
     api_flags.enable_type_checks = false;
     api_flags.enable_asserts = false;
     api_flags.enable_error_on_bad_type = false;
     api_flags.enable_error_on_bad_override = false;
-#if defined(DART_PRECOMPILER)
-    api_flags.use_field_guards = false;
-#else
+#if !defined(DART_PRECOMPILER)
     api_flags.use_field_guards = true;
+    api_flags.use_osr = true;
 #endif
 
     isolate = reinterpret_cast<Isolate*>(create_callback(
         KernelIsolate::kName, NULL, NULL, NULL, &api_flags, NULL, &error));
     if (isolate == NULL) {
       OS::PrintErr(DART_KERNEL_ISOLATE_NAME ": Isolate creation error: %s\n",
                    error);
       KernelIsolate::SetKernelIsolate(NULL);
       KernelIsolate::FinishedInitializing();
       return;
@@ skipping 351 matching lines @@
   }
 
   KernelCompilationRequest request;
   return request.SendAndWaitForResponse(kernel_port, script_uri);
 }
 
 
 #endif  // DART_PRECOMPILED_RUNTIME
 
 }  // namespace dart