Expect.throws calls its first argument, f, with no arguments.
If f isn't callable in this way, the act of calling would throw, and this throw would be considered as makeing the Expect.throws succeeede.
Now we check the argument first, and call it outside the try/catch if it's not callable. This was already caught in checked mode, but we shouldn't accept a false positive in unchecked mode either.
R=zerny@google.com
Review URL: https://codereview.chromium.org//692463002
git-svn-id: https://dart.googlecode.com/svn/branches/bleeding_edge/dart@41392 260f80e4-7a28-3924-810f-c04153c831b5
lrn@google.com
f48916d0fb