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

runtime/include/dart_api.h

 /*
  * Copyright (c) 2012, 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.
  */
 
 #ifndef RUNTIME_INCLUDE_DART_API_H_
 #define RUNTIME_INCLUDE_DART_API_H_
 
 /** \mainpage Dart Embedding API Reference
@@ skipping 602 matching lines @@
 
 #define DART_FLAGS_CURRENT_VERSION (0x00000002)
 
 typedef struct {
   int32_t version;
   bool enable_type_checks;
   bool enable_asserts;
   bool enable_error_on_bad_type;
   bool enable_error_on_bad_override;
   bool use_field_guards;
+  bool use_osr;
 } Dart_IsolateFlags;
 
 /**
  * An isolate creation and initialization callback function.
  *
  * This callback, provided by the embedder, is called when the vm
  * needs to create an isolate. The callback should create an isolate
  * by calling Dart_CreateIsolate and load any scripts required for
  * execution.
  *
@@ skipping 2709 matching lines @@
  */
 DART_EXPORT bool Dart_IsPrecompiledRuntime();
 
 
 /**
  *  Print a native stack trace. Used for crash handling.
  */
 DART_EXPORT void Dart_DumpNativeStackTrace(void* context);
 
 #endif /* INCLUDE_DART_API_H_ */ /* NOLINT */