Add a basic `stringToUTF16HexString` unit-test
Add a basic `stringToUTF16HexString` unit-test

mozilla/pdf.js,showpad/mozilla-pdf.js,Snuffleupagus/pdf.js,showpad/mozilla-pdf.js,mozilla/pdf.js,mozilla/pdf.js,Snuffleupagus/pdf.js,Snuffleupagus/pdf.js,showpad/mozilla-pdf.js