Update charted to 0.4.8 and roll

packages/petitparser/lib/src/debug/trace.dart

-part of petitparser.debug;
-
-/// Returns a transformed [parser] that when being used to read input prints a
-/// trace of all activated parsers and their respective parse results.
-///
-/// For example, the snippet
-///
-///     var parser = letter() & word().star();
-///     trace(parser).parse('f1');
-///
-/// produces the following output:
-///
-///     Instance of 'SequenceParser'
-///       Instance of 'CharacterParser'[letter expected]
-///       Success[1:2]: f
-///       Instance of 'PossessiveRepeatingParser'[0..*]
-///         Instance of 'CharacterParser'[letter or digit expected]
-///         Success[1:3]: 1
-///         Instance of 'CharacterParser'[letter or digit expected]
-///         Failure[1:3]: letter or digit expected
-///       Success[1:3]: [1]
-///     Success[1:3]: [f, [1]]
-///
-/// Indentation signifies the activation of a parser object. Reverse indentation
-/// signifies the returning of a parse result either with a success or failure
-/// context.
-Parser trace(Parser parser, [OutputHandler output = print]) {
-  var level = 0;
-  return transformParser(parser, (each) {
-    return new ContinuationParser(each, (continuation, context) {
-      output('${_repeat(level, '  ')}$each');
-      level++;
-      var result = continuation(context);
-      level--;
-      output('${_repeat(level, '  ')}$result');
-      return result;
-    });
-  });
-}