Support missing allowlisting types in filters.getAllowingFilters()
In #47 (closed), we introduced filters.getAllowingFilters()
to retrieve a list of filters that allowlist certain types of content (i.e. frame content via "document", requests via "genericblock", elements via "elemhide" and "generichide").
However, none of those types can be used to retrieve all filters that allowlist "image"/"media"/"subdocument"/"object"-type requests. Therefore we cannot determine whether an image is allowlisted before creating a filter for it in the filter composer (see adblockpluschrome/lib/filterComposer.js), because we're unable to get allowing filters such as @@$subdocument
using filters.getAllowingFilters()
.