* In expanded mode, emit characters in Unicode private-use areas as escape
sequences rather than literal characters.
* Fix a bug where quotes would be omitted for an attribute selector whose value
was a single backslash.
* Properly consider numbers that begin with `.` as "plain CSS" for the purposes
of parsing plain-CSS `min()` and `max()` functions.
* Allow `if` to be used as an unquoted string.
* Properly parse backslash escapes within `url()` expressions.
* Fix a couple bugs where `extend`s could be marked as unsatisfied when
multiple identical `extend`s extended selectors across `use` rules.
Command Line Interface
* Strip CRLF newlines from snippets of the original stylesheet that are included
in the output when an error occurs.
JS API
* Don't crash when a Windows path is returned by a custom Node importer at the
same time as file contents.
* Don't crash when an error occurs in a stylesheet loaded via a custom importer
with a custom URL scheme.
Dart API
* Add a `SassArgumentList.keywordsWithoutMarking` getter to access the keyword
arguments of an argument list without marking them accessed.