Improve String and RegExp implementations.

dart/frog/leg/lib/regexp_helper.dart

 // Copyright (c) 2012, 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.
 
 class RegExpWrapper {
   final re;
 
   // TODO(ahe): This constructor is clearly not const. We need some
   // better way to handle constant regular expressions. One might
   // question if regular expressions are really constant as we have
   // tests that expect an exception from the constructor.
   const RegExpWrapper(pattern, multiLine, ignoreCase, global)
     : re = makeRegExp(pattern, "${multiLine == true ? 'm' : ''}${
                                   ignoreCase == true ? 'i' : ''}${
                                   global == true ? 'g' : ''}");
 
+  RegExpWrapper.fromRegExp(other, global)
+    // TODO(ahe): Use redirection.

[ngeoffray, 2012/02/21 12:15:53]

Should be supported now.

+    : re = makeRegExp(other.pattern, "${other.multiLine == true ? 'm' : ''}${
+                                        other.ignoreCase == true ? 'i' : ''}${
+                                        global == true ? 'g' : ''}");
+
   exec(str) {
     var result = JS('List', @'$0.exec($1)', re, checkString(str));
     if (JS('bool', @'$0 === null', result)) return null;
     return result;
   }
 
-  lastIndex() => JS('List', @'$0.lastIndex', re);
-
-  test(str) => JS('List', @'$0.test($1)', re, checkString(str));
+  test(str) => JS('bool', @'$0.test($1)', re, checkString(str));
 
   static matchStart(m) => JS('int', @'$0.index', m);
 
   static makeRegExp(pattern, flags) {
     checkString(pattern);
     try {
       return JS('Object', @'new RegExp($0, $1)', pattern, flags);
     } catch (var e) {
       throw new IllegalJSRegExpException(pattern,
                                          JS('String', @'String($0)', e));
     }
   }
 }
+
+stringify(x) => x === null ? "" : x.toString();