Cache the fallback font dictionary on the `PartialEvaluator` (PR 11218 follow-up)
Cache the fallback font dictionary on the `PartialEvaluator` (PR 11218 follow-up)

This way we'll benefit from the existing font caching, and can thus avoid re-creating a fallback font over and over again during parsing.
(Thece changes necessitated the previous patch, since otherwise breakage could occur e.g. with fake workers.)

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