Convert some properties, on `PDFThumbnailView`-instances, to local variables
Convert some properties, on `PDFThumbnailView`-instances, to local variables

These properties are always updated/used together, and there's no other methods which depend on just one of them, hence they're changed into local variables instead.
Looking through the history of this code, it seems they were converted *from* local variables and to properties all the way back in PR 2914; however as far as I can tell from that diff it doesn't seem to have been necessary even back then!?

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