Among other languages, I've toyed some with TypeScript over the past half year or so. Lack of good IDE for my use case (Eclipse, not VS) was lacking. But now a company called Palantir has been working on a decent TypeScript plug-in for Eclipse.
I think I'm more in line with TypeScript than with Dart, and last time I tried the Dart editor (in the past month or so), it kept using high CPU all the time (maybe related to issues like this, not sure), and it was slow and flaky for its inference and code editing support. If JS really has speed limits that Dart can break, maybe I'd change my mind. Or if the Dart editor actually got any good. Don't know. For now, though, I like TypeScript better. It seems more "the right thing" to me.
Now if only Microsoft would add operator overloading to TypeScript and if someone would implement a TS to C++ compiler with full instant support for header parsing (pipe dream, maybe), I might really be able to make TypeScript my real go-to language. I'd prefer different, but it might be good enough.
As an aside, I'd really like this TS clone problem to go away, too. Even if it's a GnuTLS issue, it's only hit me at CodePlex so far as I know.