The Internet isn't a technology; it's a collection of standards. Much like the industrial revolution wasn't about mechanisms; it was about interchangeable parts and standardization of forms, such that they could be usefully combined without eternal one-off customization.

In the short-run, your approach is sound. In the large, a web technology isn't a web technology if my browser doesn't support it. Seems that the people in charge of Dart decided it had crossed the event horizon from situation 1 to situation 2.

I get the impression that other browsers have committed to never supporting NaCl or Dart, so taking the initiative to build a prototype in Chrome wouldn't help.

Not even Google took the initiative. Why didn't Google integrate the Dart VM in Chrome instead of Dartium?

I'm saying that Google should have integrated the Dart VM into Chrome even if it won't be supported by the other browser makers.

Imaging a world with each browser vendor implementing his own incompatible scripting language ... Oh wait it happened in the past and it was so ugly people used a plugin called Flash that ran the same way in every browser ...

So I am assuming you agree with the approach that Microsoft took with all the IE specific features back in the day ?

I know it resulted in some very useful features e.g. AJAX but surely a standards based approach is infinitely better.