Merge #9155

9155: internal: replace attribute with equivalent whitespace r=jonas-schievink a=jonas-schievink

This is needed to that the `TokenMap` we create contains offsets that match the source. Currently the offsets don't match because the attribute is removed, shifting all subsequent token offsets by the attribute's text length.

Currently this fix has no visible effect because we don't remap tokens in attribute macros.

bors r+

Co-authored-by: Jonas Schievink <jonasschievink@gmail.com>