Update peg parser tests to r'' strings

utils/peg/pegparser.dart

 // Copyright (c) 2011, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #library('Peg Parser');
 
 /*
  * The following functions are combinators for building Rules.
  *
  * A rule is one of the following
@@ skipping 269 matching lines @@
           : "'${state._text[state.max_pos]}'";
       message = 'Expected $expected but found $found';
     }
     int start = state.max_pos;
     int end = start;
     while (start >= 1 && state._text[start - 1] != '\n') --start;
     while (end < state._text.length && state._text[end] != '\n') ++end;
     var line = state._text.substring(start, end);
     var indicator = '';
     for (var i = 0; i < line.length && start + i < state.max_pos; i++)
-      indicator = indicator + ' ';
-    indicator = indicator + '^';
+      indicator = ' $indicator';
+    indicator = '$indicator^';
     // TODO: Convert to an exception.
     print(message);
     print(line);
     print(indicator);
     return null;
   }
 }
 
 class Symbol {
   final String name;
@@ skipping 305 matching lines @@
     sb.add(rule);
     separator = ',';
   }
   sb.add(')');
   return sb.toString();
 }
 
 class _SequenceRule extends _Rule {
   // This rule matches the component rules in order.
   final List<_Rule> _rules;
-  final int _generatingSubRules = 0;
+  final int _generatingSubRules;
   final Function _reducer;
   bool _generatesValue;
   _SequenceRule(List<_Rule> this._rules,
                 int this._generatingSubRules,
                 Function this._reducer) {
     _generatesValue = _generatingSubRules > 0 || _reducer != null;
   }
 
   _match(state, pos) {
     var sequence = [];
@@ skipping 221 matching lines @@
   add(s);
   add(t);
   add(u);
   add(v);
   add(w);
   add(x);
   add(y);
   add(z);
   return list;
 }