Grid in an invisible iframe fails to initialize - Firefox only

[SirePi]

As the title says, I have a grid in an iframe, that starts as invisible via ng-show set to a false condition.
In Chrome, this works, and once the iframe becomes visible, it works as it should.
In Firefox, gridUtil.getStyle() in the grid's controller fails on initialization, with the result that the whole grid is unuseable.
I didn't try with other browsers

relevant plunkr: http://plnkr.co/edit/yn47FW6X1ZrxAAkG1KCJ