Roll Observatory packages and add a roll script

packages/petitparser/lib/debug.dart

-/**
- * This package contains some simple debugging tools.
- */
-library debug;
+/// This package contains some simple debugging tools.
+library petitparser.debug;
 
 import 'package:petitparser/petitparser.dart';
 import 'package:petitparser/reflection.dart';
 
 part 'src/debug/continuation.dart';
 part 'src/debug/profile.dart';
 part 'src/debug/progress.dart';
 part 'src/debug/trace.dart';
 
 typedef void OutputHandler(Object object);
 
 String _repeat(int count, String value) {
   var result = new StringBuffer();
   for (var i = 0; i < count; i++) {
     result.write(value);
   }
   return result.toString();
 }