Instead of relying on GScanner and its idea of syntax, code up a parser
that obeys the CSS spec.
This also has the great side effect of reporting correct line numbers
and positions.
Also included is a reorganization of the returned error values. Instead
of error values describing what type of syntax error was returned, the
code just returns SYNTAX_ERROR. Other messages exist for when actual
values don't work or when errors shouldn't be fatal due to backwards
compatibility.
Tests in the parser need 1 or 2 files:
1) test.css
2) test.ref.css (optional, defaults to test.css)
The test instantiates a CSS provider, loads test.css, then dumps the
loaded file to test.out.css and then checks that that file matches
test.ref.css. If not, it dumps a diff between those two to the log and
fails.
You want to run the test with --verbose to get the output dumped to
stdout.
