Update `src/shared/compatibility.js` to only run with `SKIP_BABEL = false` set
Update `src/shared/compatibility.js` to only run with `SKIP_BABEL = false` set

Rather than specifying certain build targets manually, it seems much more appropriate (and future-proof) to use the `SKIP_BABEL` build target instead.

Also, the patch adds a missing `/* eslint no-var: error */` line since I'm touch the file anyway and no code-changes were necessary for it.

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