Remove unnecessary `dir`-dependent CSS rules, and simplify som findbar-button rules (PR 11077 follow-up)
Remove unnecessary `dir`-dependent CSS rules, and simplify som findbar-button rules (PR 11077 follow-up)

With the updated default viewer UI, some `dir`-dependent CSS rules are now redundant since *identical* rules are being specified for both LTR and RTL mode; after PR 12807 landed I've found even more of these cases.

Note in particular that the findbar-button rules can be simplified quite a bit, since there's a fair amount of unnecessary duplication in the CSS.

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