[src/core/fonts.js] Improve the `validateOS2Table` function
[src/core/fonts.js] Improve the `validateOS2Table` function

Rather than creating a new `Stream` just to validate the OS/2 TrueType table, it's simpler/better to just pass in a reference to the font data and use that instead (similar to other TrueType helper functions).

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