I also just realized that since the field in question is a union, this could also be a real confusion (in terms of, this was assigned as a `ContainerFrameCreationFunc` but is now misused as a `FrameCreationFunc`).
Bug 1747307 Comment 3 Edit History
Note: The actual edited comment in the bug view page will always show the original commenter’s name and original timestamp.
Alternatively we could probably change the return type of `NS_NewGridContainerFrame` to match and add casts to where this function is called explicitly (which doesn't seem to be very often). But I guess this problem here could only be the tip of the iceberg if there are more functions being used like this.