hoisted function declared inside IIFE may not return (fibers and generators modes only)

[bjouhier]

Repro:

var api = (function() {
    function foo(_, arg) {
        console.log("FOO ARG=" + arg);
        return arg + " world";
    }
    return {
        foo: foo,
    };
})();

function bar(_) {
    var result = api.foo(_, "hello");
    console.log("RESULT=" + result);    
}

bar(function(err) {
    console.log("DONE: " + err);
});

Expecting:

FOO ARG=hello
RESULT=hello world
DONE: null

but getting:

FOO ARG=hello

Notes:

• this bug only shows up in fibers and generators mode. It does not show up in callbacks mode nor in fast modes.
• this bug only occurs if function are hoisted. If function bar() is changed to var bar = function() the bug disappears. So it does not impact CoffeeScript code.