Remove failing test (arguments becoming arguments_, Issue #154) to pending
Add test for empty function with postfix if, mentioned under #48 by @twotwotwo
Add implicit function returns (#48).

Add return at the end of output functions rather than returning
a different value than the Javascript would have returned.
This patch works when the last expression in a function is a plain
expression or an if statement, but switch statements don't correctly
handle returns yet.