Update charted to 0.4.8 and roll

packages/petitparser/lib/src/json/grammar.dart

-part of petitparser.json;
-
-/// JSON grammar.
-class JsonGrammar extends GrammarParser {
-  JsonGrammar() : super(const JsonGrammarDefinition());
-}
-
-/// JSON grammar definition.
-class JsonGrammarDefinition extends GrammarDefinition {
-  const JsonGrammarDefinition();
-
-  start() => ref(value).end();
-  token(p) => p.flatten().trim();
-
-  array() => ref(token, char('['))
-      & ref(elements).optional()
-      & ref(token, char(']'));
-  elements() => ref(value).separatedBy(ref(token, char(',')), includeSeparators: false);
-  members() => ref(pair).separatedBy(ref(token, char(',')), includeSeparators: false);
-  object() => ref(token, char('{'))
-      & ref(members).optional()
-      & ref(token, char('}'));
-  pair() => ref(stringToken)
-      & ref(token, char(':'))
-      & ref(value);
-  value() => ref(stringToken)
-      | ref(numberToken)
-      | ref(object)
-      | ref(array)
-      | ref(trueToken)
-      | ref(falseToken)
-      | ref(nullToken);
-
-  trueToken() => ref(token, string('true'));
-  falseToken() => ref(token, string('false'));
-  nullToken() => ref(token, string('null'));
-  stringToken() => ref(token, ref(stringPrimitive));
-  numberToken() => ref(token, ref(numberPrimitive));
-
-  characterPrimitive() => ref(characterNormal)
-      | ref(characterEscape)
-      | ref(characterUnicode);
-  characterNormal() => pattern('^"\\');
-  characterEscape() => char('\\')
-      & pattern(new List.from(jsonEscapeChars.keys).join());
-  characterUnicode() => string('\\u')
-      & pattern("0-9A-Fa-f").times(4);
-  numberPrimitive() => char('-').optional()
-      & char('0').or(digit().plus())
-      & char('.').seq(digit().plus()).optional()
-      & pattern('eE').seq(pattern('-+').optional()).seq(digit().plus()).optional();
-  stringPrimitive() => char('"')
-      & ref(characterPrimitive).star()
-      & char('"');
-
-}
-
-const jsonEscapeChars = const {
-  '\\': '\\',
-  '/': '/',
-  '"': '"',
-  'b': '\b',
-  'f': '\f',
-  'n': '\n',
-  'r': '\r',
-  't': '\t'
-};