This method has an odd flaw that we don't emulate yet. Actually, two:
1. Precision limits that are specific to the chosen radix
2. Occasional and intermittent corruption in the resulting 0 padding; usually manifesting as `x`, `W`, or `°` characters
The first could be emulated, but I've chosen not to... because the second thing listed not only isn't really possible to emulate, but actively prohibits approx-testing the results. So I'm marking the test as ignored and hoping no movies actually rely on the precision limits in `toString`.
Flash preserves spaces before and after text.
But since now `quick-xml` might emit empty `Text` events, those need
to be explicitly ignored in order to retain the same text format across
tags.
This is a little tricky, because we have to map the utf8 indices
returned by the regex engine to utf16 indices usable by Ruffle.
To limit the impact on performance, the regex, the string we're
currently matching on, and the last known (utf8, utf16) positions
are cached, avoiding extra utf8 conversions in common use cases
where a single string is repeatedly searched with increasing
`lastIndex`.
This generally means that methods are more efficient, as we
don't need to encode to UTF16 on-the-fly to have correct indices.
This also fix some bugs:
- charCode now properly handle surrogate pairs
- calling lastIndexOf with the empty pattern and an OoB index now
properly returns the string length
Still missing is AVM2's String.match
These types represent an UCS2 string (UTF-16 with unpaired surrogates).
The string is stored either as a sequence of u8s (Bytes) or u16s (Wide);
the type of string is tracked by setting the high bit of the length of
its fat pointer.
The fix in #5218 wasn't sufficient; 30-bit arithmetic should be used
along all the way when calculating an effective sound transform.
For example, a sound transform composited by volumes `-0x80000000` and
`25` should end up as effectively 0, whereas previously it would have
been calculated as `-0x80000000 * 25 / 100 = -0x20000000`, which is a
30-bit integer that hasn't been truncated.
Fixes#5655.