Roll Observatory packages and add a roll script

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

-part of smalltalk;
+part of petitparser.smalltalk;
 
-/**
- * Smalltalk grammar.
- */
+/// Smalltalk grammar.
 class SmalltalkGrammar extends GrammarParser {
   SmalltalkGrammar() : super(new SmalltalkGrammarDefinition());
 }
 
-/**
- * Smalltalk grammar definition.
- */
+/// Smalltalk grammar definition.
 class SmalltalkGrammarDefinition extends GrammarDefinition {
 
   // the original implementation used a handwritten parser to
   // build special token objects
   token(input) {
     if (input is String) {
       input = input.length == 1 ? char(input) : string(input);
     }
     return input.token().trim(ref(spacer));
   }
@@ skipping 197 matching lines @@
       .seq(char(':').not());
   unaryExpression() => ref(primary)
       .seq(ref(unaryMessage).star());
   unaryMessage() => ref(unaryToken);
   unaryMethod() => ref(identifierToken);
   unaryPragma() => ref(identifierToken);
   unaryToken() => ref(token, ref(unary));
   variable() => ref(identifierToken);
 
 }