incremental progress on Value

frog/lib/corelib_impl.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("dart:coreimpl");
 
 #source("../../corelib/src/implementation/dual_pivot_quicksort.dart");
 #source("../../corelib/src/implementation/duration_implementation.dart");
 #source("../../corelib/src/implementation/exceptions.dart");
 #source("../../corelib/src/implementation/future_implementation.dart");
@@ skipping 236 matching lines @@
 
   Match firstMatch(String str) native
   '''var m = this.re.exec(str);
   return m && new MatchImplementation(
       this.pattern, str, m.index, this.re.lastIndex, m);''';
 
   bool hasMatch(String str) native "return this.re.test(str);";
 
   String stringMatch(String str) {
     var match = firstMatch(str);
-    return match && match.group(0);
+    return match === null ? null : match.group(0);
   }
 
   Iterable<Match> allMatches(String str) => new _AllMatchesIterable(this, str);
 }
 
 class MatchImplementation implements Match {
   const MatchImplementation(
       String this.pattern,
       String this.str,
       int this._start,
@@ skipping 138 matching lines @@
     } else if (isNaN()) {
       if (other.isNaN()) {
         return 0;
       }
       return 1;
     } else {
       return -1;
     }
   }
 }