Is there a REPL for Dart to experiment with?
I tried inputing dart code in DevTools in Dartium and that also didn't work.
So I couldn't find an easy way to play with various APIs in dart.
Though it is not really a REPL, you may find the Try Dart online tool useful for playing around. It's a bit slow, since it is actually compiling the Dart code to JavaScript in order to have it work within the browser.
There is also a console that someone built, which is probably better if you're looking for a real REPL, but it requires a bit of setup.