Add img element at the icons for line comments. Enable screen readers recognize the icons.

gistfile1.txt

(function() {
var elements = document.getElementsByTagName( '*' );
for ( var i = 0, il = elements.length; i < il; i++ ) {
 var element = elements[i];
 if ( /\bmini-icon-add-comment\b/.test( element.className ) ) {
  var img = document.createElement("img");
  img.setAttribute("alt", "*");
  element.appendChild(img);
 }
}
})();