On one occasion Mozilla has argued that the speed difference between a) non-JS code running natively and b) the same code rewritten in, or even compiled to, JS is (or soon will be) too small to be important. Now on this occasion Mozilla is arguing that the speed difference between a) native-VM Dart and b) Dart-to-JS is (and will remain) large enough to be important. I pointed out that these two claims are hard to reconcile. About the only way they can both be mostly-true is if the performance gap only happens to be large and important enough on exactly those occasions when that gap happens to bite Mozilla in its platform strategy. Not very likely, unless one assumes that the performance needs of the poor sods who just want to use the web (as publishers or consumers) are never all that important.
So the fact that Mozilla's problems with the relatively poor performance of Dart-to-JS would be solved if native-VM Dart went away has little relevance, because most other people's problems with the speed of JS are not helped by making there be no alternative to JS.
> or go back to school and learn how to argue