[api] Add documentation for PropertyQueryCallback.

include/v8.h

Index: include/v8.h
diff --git a/include/v8.h b/include/v8.h
index 8fc9149671a9795d3a797e543d8f8ae4f29c3ba6..e65a374966f6fa6ef5ed3b3d594fe97512e5a312 100644
--- a/include/v8.h
+++ b/include/v8.h
@@ -4543,11 +4543,25 @@ typedef void (*GenericNamedPropertySetterCallback)(
     Local<Name> property, Local<Value> value,
     const PropertyCallbackInfo<Value>& info);
 
-
 /**
- * Returns a non-empty handle if the interceptor intercepts the request.
- * The result is an integer encoding property attributes (like v8::None,
- * v8::DontEnum, etc.)
+ * Intercepts all requests that query the attributes of the
+ * property, e.g., getOwnPropertyDescriptor(), propertyIsEnumerable(), and
+ * defineProperty().
+ *
+ * Use `info.GetReturnValue().Set(value)` to set the property attributes. The
+ * value is an interger encoding a `v8::PropertyAttribute`.
+ *
+ * \param property The name of the property for which the request was
+ * intercepted.
+ * \param info Information about the intercepted request, such as
+ * isolate, receiver, return value, or whether running in `'use strict'` mode.
+ * See `PropertyCallbackInfo`.
+ *
+ * \note hasOwnProperty() can trigger this interceptor, but for optimization
+ * reasons it is not guaranteed to.

[jochen (gone - plz use gerrit), 2016/08/29 12:52:35]

wut? :-/

[Franzi, 2016/08/31 11:18:36]

Is this version better or should we leave out the note? 

[jochen (gone - plz use gerrit), 2016/08/31 14:37:49]

ah, so you mean that hasOwnProperty might or might not call this specific
callback, but it will always call some callback on the interceptor?

+ *
+ * See also
+ * `ObjectTemplate::SetNamedPropertyHandler.`
  */
 typedef void (*GenericNamedPropertyQueryCallback)(
     Local<Name> property, const PropertyCallbackInfo<Integer>& info);