How well does Dart interact with JavaScript, especially libraries that are asynchronously loaded? I know that the Dart compiler is a whole-program optimizer, and I get the impression that Dart wants to own all the code on the page.
In my line of work (web analytics), I have to use third-party JavaScript libraries in order to integrate tools onto my page, like Adobe Analytics (formerly Omniture SiteCatalyst) or IBM CoreMetrics or WebTrends. Fully instrumenting a page generally involves wiring up other JavaScript on the page with event handlers for web analytics functions (e.g. video play/pause/progress, with video name & length as parameters).
Most analytics tools are also moving towards asychronously-loaded script-injection techniques, like Adobe DTM or Ensighten. These usually include the ability to selectively load relevant libraries, like only having video tracking on video pages.
What's Dart's story for interacting with tools like that?