Follow-ups to the review of #4697 and #4698:
- With textAs: outlines, a .ai saved without PDF compatibility, read
from its editing data alone, has its type outlined too, as an empty
page or a text-only placeholder already did.
- Threaded type read from the editing data holds its story in its first
frame: it now flows through its frames before it is outlined, so each
frame's outlines show the text it holds, and the outlined frames
leave their threads.
- Each outline group keeps its type's opacity, blend mode, isolation,
opacity mask and effects (the same carry-over the flattener uses).
- A gradient-mesh corner (/N) holding anything but numbers is unread,
instead of being read with the numbers after it shifted into its
colour and opacity.