Repl is doing double evaluation of code: wrapped in parens and without
them. That's needed to allow users typing multiline chunks of code by
handling syntax errors on repl side. However if function declaration is
wrapped in parens (`(function a() {})`) calling it will be impossible,
so we're evaluating functions twice. That works fine for declaration,
but if entered code chunk returns function - it should not be called
twice.
fix#2773
ae5e23310e