Make int a double in argument type checks.

sdk/lib/_internal/compiler/implementation/lib/native_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.
 
 part of _js_helper;
 
 String typeNameInChrome(obj) {
   String name = JS('String', "#.constructor.name", obj);
   return typeNameInWebKitCommon(name);
 }
@@ skipping 59 matching lines @@
   if (name == 'Object') {
     if (JS('bool', 'window.DataView && (# instanceof window.DataView)', obj)) {
       return 'DataView';
     }
   }
   return name;
 }
 
 String constructorNameFallback(object) {
   if (object == null) return 'Null';
+  object = getInterceptor(object);
   var constructor = JS('var', "#.constructor", object);
   if (identical(JS('String', "typeof(#)", constructor), 'function')) {
     var name = JS('var', r'#.builtin$cls', constructor);
     if (name != null) return name;
     // The constructor isn't null or undefined at this point. Try
     // to grab hold of its name.
     name = JS('var', '#.name', constructor);
     // If the name is a non-empty string, we use that as the type
     // name of this object. On Firefox, we often get 'Object' as
     // the constructor name even for more specialized objects so
@@ skipping 211 matching lines @@
   }
   var isLeaf =
       (leafTags != null) && JS('bool', '(#[#]) === true', leafTags, tag);
   if (isLeaf) {
     return makeDispatchRecord(interceptor, false, null);
   } else {
     var proto = JS('', 'Object.getPrototypeOf(#)', obj);
     return makeDispatchRecord(interceptor, proto, null);
   }
 }