Example: richText editor 1 and 2 both have UploadFeature. richText
editor 1 calls UploadFeature() with custom fields, richText editor 2
calls UploadFeature() with NO custom fields. Before this PR, richText
editor 1 would not have had any custom fields, as richText editor 2 will
override the feature object (specifically its props).
2f3829083d