Fix dartium bug handling object literal constructors with zero arguments.

sdk/lib/js/dartium/js_dartium.dart

 // Copyright (c) 2013, 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.
 
 /**
  * Support for interoperating with JavaScript.
  *
  * This library provides access to JavaScript objects from Dart, allowing
  * Dart code to get and set properties, and call methods of JavaScript objects
  * and invoke JavaScript functions. The library takes care of converting
@@ skipping 392 matching lines @@
         if (_hasJsName(clazz)) {
           // TODO(jacobr): verify class implements JavaScriptObject.
           String jsClassName = _getJsMemberName(clazz);
           var className = mirrors.MirrorSystem.getName(clazz.simpleName);
           var sbPatch = new StringBuffer();
           jsInterfaceTypes.add(clazz);
           clazz.declarations.forEach((name, declaration) {
             if (declaration is! mirrors.MethodMirror ||
                 !_isExternal(declaration)) return;
             if (declaration.isFactoryConstructor && _isAnonymousClass(clazz)) {
-              sbPatch.write("  factory ${className}({");
+              sbPatch.write("  factory ${className}(");
               int i = 0;
               var args = <String>[];
               for (var p in declaration.parameters) {
                 args.add(mirrors.MirrorSystem.getName(p.simpleName));
                 i++;
               }
-              sbPatch
-                ..write(
-                    args.map((name) => '$name:${_UNDEFINED_VAR}').join(", "))
-                ..write("}) {\n"
+              if (args.isNotEmpty) {
+                sbPatch
+                  ..write('{')
+                  ..write(
+                      args.map((name) => '$name:${_UNDEFINED_VAR}').join(", "))
+                  ..write('}');
+              }
+              sbPatch.write(") {\n"
                     "    var ret = new ${_JS_LIBRARY_PREFIX}.JsObject.jsify({});\n");
               i = 0;
               for (var p in declaration.parameters) {
                 assert(p.isNamed); // XXX throw
                 var name = args[i];
                 var jsName = mirrors.MirrorSystem.getName(p.simpleName);
                 // XXX apply name conversion rules.
                 sbPatch.write(
                     "    if($name != ${_UNDEFINED_VAR}) ret['$jsName'] = $name;\n");
                 i++;
@@ skipping 921 matching lines @@
     return f;
   } else {
     var ret = _interopCaptureThisExpando[f];
     if (ret == null) {
       ret = new JsFunction.withThis(f);
       _interopCaptureThisExpando[f] = ret;
     }
     return ret;
   }
 }