When you put "Google" in a sentence with Dart, "Monopoly" starts to sound different. I read your sentence as :

"Google is changing the monopoly of JavaScript by implementing the Dart VM in their own browser."

As far as I know community doesn't care much about Dart [1] and they are concentrating on further enhancement on ECMAScript.

[1] : http://en.wikipedia.org/wiki/Dart_%28programming_language%29...