Firefox userChrome.js greasemonkeyスクリプトｽﾚ46

_getLinkTEXT: function(aNode) {
if (!aNode)
return "";
let text = this._gatherTextUnder(aNode);

を

_getLinkTEXT: function(aNode) {
if (!aNode)
return "";

/*リンクでないなら""*/
if (!(aNode instanceof content.HTMLAnchorElement ||
aNode instanceof content.HTMLAreaElement)) {
return "";
}

let text = this._gatherTextUnder(aNode);

とか?