[api-minor] Ensure that the `Array.prototype` doesn't contain any enumerable properties
[api-minor] Ensure that the `Array.prototype` doesn't contain any enumerable properties

Over the years there's been a fair number of issues/PRs opened, where people have wanted to add `hasOwnProperty` checks in (hot) loops in the font parsing code. This has always been rejected, since we don't want to risk reducing performance in the Firefox PDF viewer simply because some users of the general PDF.js library are *incorrectly* extending the `Array.prototype` with enumerable properties.

With this patch the general PDF.js library will now fail immediately with a hopefully useful Error message, rather than having (some) fonts fail to render, when the `Array.prototype` is incorrectly extended.

Note that I did consider making this a warning, but ultimately decided against it since it's first of all possible to disable those (with the `verbosity` parameter). Secondly, even when printed, warnings can be easy to overlook and finally a warning may also *seem* OK to ignore (as opposed to an actual Error).

Shoobx/pdf.js,Shoobx/pdf.js,xavier114fch/pdf.js,timvandermeij/pdf.js,macroplant/pdf.js,mozilla/pdf.js,showpad/mozilla-pdf.js,showpad/mozilla-pdf.js,Shoobx/pdf.js,nawawi/pdf.js,nawawi/pdf.js,showpad/mozilla-pdf.js,timvandermeij/pdf.js,macroplant/pdf.js,caremerge/pdf.js,timvandermeij/pdf.js,mozilla/pdf.js,Snuffleupagus/pdf.js,xavier114fch/pdf.js,Snuffleupagus/pdf.js,caremerge/pdf.js,Snuffleupagus/pdf.js,macroplant/pdf.js,nawawi/pdf.js,mozilla/pdf.js