[js-interop] Fix function binding and avoid noSuchMethod when using map notation

test/js/browser_tests_bootstrap.js

 // 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.
 
 var x = 42;
 
 var _x = 123;
 
 var myArray = ["value1"];
 
 var foreignDoc = (function(){
   var doc = document.implementation.createDocument("", "root", null);
   var element = doc.createElement('element');
   element.setAttribute('id', 'abc');
   doc.documentElement.appendChild(element);
   return doc;
 })();
 
 function razzle() {
   return x;
 }
 
+function varArgs() {
+  var args = arguments;
+  var sum = 0;
+  for (var i = 0; i < args.length; ++i) {
+    sum += args[i];
+  }
+  return sum;
+}
+
 function Foo(a) {
   this.a = a;
 }
 
+Foo.b = 38;
+
 Foo.prototype.bar = function() {
   return this.a;
 }
 
+var container = new Object();
+container.Foo = Foo;
+
 function isArray(a) {
   return a instanceof Array;
 }
 
 function checkMap(m, key, value) {
   if (m.hasOwnProperty(key))
     return m[key] == value;
   else
     return false;
 }
@@ skipping 28 matching lines @@
 
 function testJsMap(callback) {
   var result = callback();
   return result['value'];
 }
 
 function Bar() {
   return "ret_value";
 }
 Bar.foo = "property_value";