The fallbacks on the platform should ideally contain all fonts that
support the script passed in, but this would require populating the
font database and checking the unicode ranges for all fonts, so it
would cause a significant performance hit on Mac. What we do here
instead is just return a set of default fonts as the fallbacks
and disregard the requested script.
The consequence of this is that some special unicode codepoints were
not supported on Mac, because we weren't working with a full fallback
list.
To rectify this without breaking performance, we always add Arial
Unicode MS to the end of the fallback list as a final fallback.
This should always be present on the system and has a wide support
of different scripts.
[ChangeLog][OS X][Fonts] Fixed missing glyph box shown in place of some
uncommon Unicode code points.
Change-Id: I4fc8576bfddc8a73204aca2b16437d42c524bc79
Task-number: QTBUG-40986
Task-number: QTBUG-40549
Reviewed-by: Tor Arne Vestbø <tor.arne.vestbo@digia.com>
a614bc6e39