Implement operator-is for interfaces' supertypes and String's supertypes. Also, improve stack trace…

dart/frog/leg/lib/js_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.
 
 #library('js_helper');
 
 #import('coreimpl.dart');
 
 #source('date_helper.dart');
 #source('regexp_helper.dart');
@@ skipping 1154 matching lines @@
     throw 'String.hashCode is not implemented';
   }
   if (isJsArray(receiver)) {
     throw 'List.hashCode is not implemented';
   }
   return UNINTERCEPTED(receiver.hashCode());
 }
 
 // TODO(ahe): Dynamic may be overridden.
 builtin$get$dynamic(receiver) => receiver;
+
+/**
+ * Called by generated code to capture the stacktrace before throwing
+ * an exception.
+ */
+captureStackTrace(ex) {
+  return ex;

[ngeoffray, 2012/02/22 11:12:36]

Remove this line.

[ahe, 2012/02/22 21:51:24]

Done.

+  if (ex === null) return ex;

[ngeoffray, 2012/02/22 11:12:36]

You could change that to:
if (JS('bool', @'typeof $0 !== "object"', ex)) return ex;

[ahe, 2012/02/22 21:51:24]

Great idea!

+  if (JS('bool', @'typeof $0 === "object"', ex)) {
+    var hasCapture = JS('bool', @'!!(Error.captureStackTrace)');
+    if (hasCapture) {
+      JS('Object', @'Error.captureStackTrace($0)', ex);
+    }
+  }
+  return ex;
+}