[TextLayer] Only handle positive padding values in `expandTextDivs`
[TextLayer] Only handle positive padding values in `expandTextDivs`

Given that browsers will reject padding values smaller than zero (which may be caused by limited numerical precision during calculations in the `expand` code), it makes no sense to include those when expanding the `textDiv`s.

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