fixes #232, handling of arguments

lib/runtime/dart/core.js

 dart_library.library('dart/core', null, /* Imports */[
   "dart_runtime/dart"
 ], /* Lazy imports */[
   'dart/_js_helper',
   'dart/_internal',
   'dart/collection',
   'dart/_interceptors',
   'dart/convert'
 ], function(exports, dart, _js_helper, _internal, collection, _interceptors, convert) {
   'use strict';
   let dartx = dart.dartx;
   class Object {
     constructor() {
       let name = this.constructor.name;
-      let init = this[name];
       let result = void 0;
-      if (init)
-        result = init.apply(this, arguments);
+      if (name in this)
+        result = this[name](...arguments);
       return result === void 0 ? this : result;
     }
     ['=='](other) {
       return identical(this, other);
     }
     get hashCode() {
       return _js_helper.Primitives.objectHashCode(this);
     }
     toString() {
       return _js_helper.Primitives.objectToString(this);
@@ skipping 3337 matching lines @@
   exports.StackTrace = StackTrace;
   exports.Stopwatch = Stopwatch;
   exports.String = String;
   exports.RuneIterator = RuneIterator;
   exports.StringBuffer = StringBuffer;
   exports.StringSink = StringSink;
   exports.Symbol = Symbol;
   exports.Type = Type;
   exports.Uri = Uri;
 });