Having two ways that `<position>` is represented is awkward and
unnecessary. So, let's combine the two paths together. This first step
copies and modifies the `parse_position()` code to produce a
`PositionStyleValue`.
Apart from returning a StyleValue, this also makes use of automatic enum
parsing instead of manually comparing identifier strings.
Display a warning when some images are missing, instead of crashing.
Also, don't keep old images around when loading a new set, and make use
of get_piece_graphic() more often.
Previously we would give up on loading the piece images if one fails.
That was awkward because 2 out of 3 places where `set_piece_set_name()`
is called can't propagate errors, so we'd just crash.
Instead, let's skip any images that fail to load, and then when painting
the preview, skip any missing bitmaps and show a warning message that
some are missing.
This will be required for propagating the current animation time to all
relevant timelines, which each propagate that time to all of their
relevant animations.
This does _NOT_ correspond to anything in the IDL or ECMAScript spec,
but is a custom extended attribute.
We use it to define the "enumerated" values of an attribute
Instead of a StringView. This allows us to preserve the nice O(1) string
compare property of FlyString, and not needing to allocate when one is
needed.
Ideally all other places in Token should have similar changes done, but
to prevent a huge amount of churn, just change ident for now.
https://cldr.unicode.org/index/downloads/cldr-44
Notable changes that affect us include:
* The Islamic Calendar is now localized as the Hijri Calender (in en-US)
but has not been updated for all locales. So this patch updates tests
where possible and removes a few test cases that currently cannot be
localized.
* The und locale has received more likely subtag data (the und locale is
basically a pseudo-locale meaning "undetermined").
* The exponential symbol in the Arabic number system was changed from
U+0627 to U+0623.
