This is only temporary; once all code paths use the ruffle `WString` API instead of dereferencing to a string, the UTF8 `String` will be removed.
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.