Doesn't dart actually do type checking? It's been a month or 2 since I played with it, but I could swear that it did type checking and reported errors when the type was wrong.
It has a "checked mode" and an unchecked mode, but they recommend the checks be disabled in production. The unchecked mode is actually called "production mode" in a lot of their documentation, including the language spec. (See the section on "types".)
