Fix dartium crasher, use DARTSCOPE when getting/setting native fields as it creates a Handle.

runtime/vm/dart_api_impl.cc

 // Copyright (c) 2013, 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 "include/dart_api.h"
 #include "include/dart_mirrors_api.h"
 #include "include/dart_native_api.h"
 
 #include "platform/assert.h"
 #include "vm/bigint_operations.h"
@@ skipping 528 matching lines @@
   } else {
     CHECK_CALLBACK_STATE(isolate);
     // This is a VM internal object. Call the C++ method of printing.
     return Api::NewHandle(isolate, String::New(obj.ToCString()));
   }
 }
 
 
 DART_EXPORT bool Dart_IdentityEquals(Dart_Handle obj1, Dart_Handle obj2) {
   Isolate* isolate = Isolate::Current();
-  CHECK_ISOLATE(isolate);
+  DARTSCOPE(isolate);
   {
     NoGCScope ngc;
     if (Api::UnwrapHandle(obj1) == Api::UnwrapHandle(obj2)) {
       return true;
     }
   }
   const Object& object1 = Object::Handle(isolate, Api::UnwrapHandle(obj1));
   const Object& object2 = Object::Handle(isolate, Api::UnwrapHandle(obj2));
   if (object1.IsInstance() && object2.IsInstance()) {
     return Instance::Cast(object1).IsIdenticalTo(Instance::Cast(object2));
@@ skipping 3221 matching lines @@
 
 DART_EXPORT Dart_Handle Dart_GetNativeInstanceFieldCount(Dart_Handle obj,
                                                          int* count) {
   Isolate* isolate = Isolate::Current();
   CHECK_ISOLATE(isolate);
   ReusableObjectHandleScope reused_obj_handle(isolate);
   const Instance& instance = Api::UnwrapInstanceHandle(reused_obj_handle, obj);
   if (instance.IsNull()) {
     RETURN_TYPE_ERROR(isolate, obj, Instance);
   }
-  const Class& cls = Class::Handle(isolate, instance.clazz());
-  *count = cls.num_native_fields();
+  *count = instance.NumNativeFields();
   return Api::Success();
 }
 
 
 DART_EXPORT Dart_Handle Dart_GetNativeInstanceField(Dart_Handle obj,
                                                     int index,
                                                     intptr_t* value) {
   Isolate* isolate = Isolate::Current();
-  CHECK_ISOLATE(isolate);
+  DARTSCOPE(isolate);
   ReusableObjectHandleScope reused_obj_handle(isolate);
   const Instance& instance = Api::UnwrapInstanceHandle(reused_obj_handle, obj);
   if (instance.IsNull()) {
     RETURN_TYPE_ERROR(isolate, obj, Instance);
   }
   if (!instance.IsValidNativeIndex(index)) {
     return Api::NewError(
         "%s: invalid index %d passed in to access native instance field",
         CURRENT_FUNC, index);
   }
   *value = instance.GetNativeField(index);
   return Api::Success();
 }
 
 
 DART_EXPORT Dart_Handle Dart_SetNativeInstanceField(Dart_Handle obj,
                                                     int index,
                                                     intptr_t value) {
   Isolate* isolate = Isolate::Current();
-  CHECK_ISOLATE(isolate);
+  DARTSCOPE(isolate);
   ReusableObjectHandleScope reused_obj_handle(isolate);
   const Instance& instance = Api::UnwrapInstanceHandle(reused_obj_handle, obj);
   if (instance.IsNull()) {
     RETURN_TYPE_ERROR(isolate, obj, Instance);
   }
   if (!instance.IsValidNativeIndex(index)) {
     return Api::NewError(
         "%s: invalid index %d passed in to set native instance field",
         CURRENT_FUNC, index);
   }
@@ skipping 776 matching lines @@
 
 
 DART_EXPORT void Dart_RegisterRootServiceRequestCallback(
     const char* name,
     Dart_ServiceRequestCallback callback,
     void* user_data) {
   Service::RegisterRootEmbedderCallback(name, callback, user_data);
 }
 
 }  // namespace dart