Fix {{action}} with params bug

The bug was introduced on https://github.com/emberjs/ember.js/commit/99619019273e51b412172103720e4d7b6a2919b6#L4R25

It may be related to #1839.

I've completely failed to understand what's behind this piece of code but this seems to fix it and my application continued working as expected.

Please, if you were so kind to provide further indications or insight I could try to write a proper test.

Sorry for such a low quality PR :crying_cat_face: