Add GetPropertyAttribute method for Object in the API

src/objects.cc

 // Copyright 2011 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 2621 matching lines @@
         return result->holder()->GetPropertyAttributeWithInterceptor(
             JSObject::cast(receiver), name, continue_search);
       default:
         UNREACHABLE();
     }
   }
   return ABSENT;
 }
 
 
+PropertyAttributes JSReceiver::TryGetPropertyAttribute(
+    Handle<Object> key,
+    bool* has_pending_exception) {
+  Isolate* isolate = GetIsolate();
+  HandleScope scope(isolate);
+  Handle<String> name;
+  if (key->IsString()) {
+    name = Handle<String>::cast(key);
+  } else {
+    Handle<Object> converted =
+        Execution::ToString(key, has_pending_exception);
+    if (*has_pending_exception) return NONE;
+    name = Handle<String>::cast(converted);
+  }
+  PropertyAttributes attr = GetPropertyAttributeWithReceiver(this, *name);
+  // Returns NONE when the property doesn't exist.
+  if (attr == ABSENT) return NONE;
+  return attr;
+}
+
+
 PropertyAttributes JSReceiver::GetLocalPropertyAttribute(String* name) {
   // Check whether the name is an array index.
   uint32_t index = 0;
   if (IsJSObject() && name->AsArrayIndex(&index)) {
     if (JSObject::cast(this)->HasLocalElement(index)) return NONE;
     return ABSENT;
   }
   // Named property.
   LookupResult result;
   LocalLookup(name, &result);
@@ skipping 9100 matching lines @@
   if (break_point_objects()->IsUndefined()) return 0;
   // Single beak point.
   if (!break_point_objects()->IsFixedArray()) return 1;
   // Multiple break points.
   return FixedArray::cast(break_point_objects())->length();
 }
 #endif
 
 
 } }  // namespace v8::internal