Harden _Q.push wrapper in the amzn_apstag.js shim

[kzar]

Apstag calls are queued onto the window.apstag._Q array and are then
called when the Apstag script is ready. The shim expects each queued
call to be an array containing the API method name prefix and
arguments, e.g.

["f", {slots: [...], timeout: 3000}, () => { ... }]

I noticed in practice however, some calls are queued differently, with a
queued call looking something like this instead:

[["f", Arguments([{slots: [...], timeout: 3000}, () => { ... }])]]

Since the original script handles that, the shim needs to as
well. Let's try our best here, without changing too much and risking
further breakage.

[dharb]

Looks good to me, thanks @kzar!