[BUGFIX beta] Ensure compat helpers calling options.fn work.

[rwjblue]

Fixes tildeio/htmlbars#270.

[rwjblue]

Updated per discussion with @mmun.

[thejchap]

@rwjblue Should options.inverse() be included in this as well?

[ritesh83]

We have a custom handlerbars helper.
It works fine with ember 1.8 but not with 1.10

In the initializer, we have:

    app.inject('helper', 'aclService', 'service:acl');

and in our helper:

    export default function(value, options) {
        var userAcl = this.get('aclService');   

        if(userAcl.get('isAdmin')) {
            return value.fn(this);
        } else {
            return value.inverse(this);  
        }
    }

The 'aclService' is now undefined in ember 1.10 (injections not working on helpers) and also the options.inverse was a function before but now it is an object (not callable).

Any suggestions on how to make it work in ember 1.10?

[pixelhandler]

@rwjblue this seems related #10812 correct?