I've included 2 functions from php.js at the top of the file. They're…

… hefty functions and can possibly be trimmed or maybe moved to another file.

Fixes issue with html entities appearing in the notification (' etc when using '). Feel free to cleanup, I just needed to get a quick fix for this.

extension.js

@@ -8,6 +8,176 @@
  *
  */
 
+/** Taken from php.js **/
+function get_html_translation_table (table, quote_style) {
+    var entities = {},
+        hash_map = {},
+        decimal = 0,
+        symbol = '';
+    var constMappingTable = {},
+        constMappingQuoteStyle = {};
+    var useTable = {},
+        useQuoteStyle = {};
+
+    // Translate arguments
+    constMappingTable[0] = 'HTML_SPECIALCHARS';
+    constMappingTable[1] = 'HTML_ENTITIES';
+    constMappingQuoteStyle[0] = 'ENT_NOQUOTES';
+    constMappingQuoteStyle[2] = 'ENT_COMPAT';
+    constMappingQuoteStyle[3] = 'ENT_QUOTES';
+
+    useTable = !isNaN(table) ? constMappingTable[table] : table ? table.toUpperCase() : 'HTML_SPECIALCHARS';
+    useQuoteStyle = !isNaN(quote_style) ? constMappingQuoteStyle[quote_style] : quote_style ? quote_style.toUpperCase() : 'ENT_COMPAT';
+
+    if (useTable !== 'HTML_SPECIALCHARS' && useTable !== 'HTML_ENTITIES') {
+        throw new Error("Table: " + useTable + ' not supported');
+        // return false;
+    }
+
+    entities['38'] = '&';
+    if (useTable === 'HTML_ENTITIES') {
+        entities['160'] = ' ';
+        entities['161'] = '¡';
+        entities['162'] = '¢';
+        entities['163'] = '£';
+        entities['164'] = '¤';
+        entities['165'] = '¥';
+        entities['166'] = '¦';
+        entities['167'] = '§';
+        entities['168'] = '¨';
+        entities['169'] = '©';
+        entities['170'] = 'ª';
+        entities['171'] = '«';
+        entities['172'] = '¬';
+        entities['173'] = '­';
+        entities['174'] = '®';
+        entities['175'] = '¯';
+        entities['176'] = '°';
+        entities['177'] = '±';
+        entities['178'] = '²';
+        entities['179'] = '³';
+        entities['180'] = '´';
+        entities['181'] = 'µ';
+        entities['182'] = '¶';
+        entities['183'] = '·';
+        entities['184'] = '¸';
+        entities['185'] = '¹';
+        entities['186'] = 'º';
+        entities['187'] = '»';
+        entities['188'] = '¼';
+        entities['189'] = '½';
+        entities['190'] = '¾';
+        entities['191'] = '¿';
+        entities['192'] = 'À';
+        entities['193'] = 'Á';
+        entities['194'] = 'Â';
+        entities['195'] = 'Ã';
+        entities['196'] = 'Ä';
+        entities['197'] = 'Å';
+        entities['198'] = 'Æ';
+        entities['199'] = 'Ç';
+        entities['200'] = 'È';
+        entities['201'] = 'É';
+        entities['202'] = 'Ê';
+        entities['203'] = 'Ë';
+        entities['204'] = 'Ì';
+        entities['205'] = 'Í';
+        entities['206'] = 'Î';
+        entities['207'] = 'Ï';
+        entities['208'] = 'Ð';
+        entities['209'] = 'Ñ';
+        entities['210'] = 'Ò';
+        entities['211'] = 'Ó';
+        entities['212'] = 'Ô';
+        entities['213'] = 'Õ';
+        entities['214'] = 'Ö';
+        entities['215'] = '×';
+        entities['216'] = 'Ø';
+        entities['217'] = 'Ù';
+        entities['218'] = 'Ú';
+        entities['219'] = 'Û';
+        entities['220'] = 'Ü';
+        entities['221'] = 'Ý';
+        entities['222'] = 'Þ';
+        entities['223'] = 'ß';
+        entities['224'] = 'à';
+        entities['225'] = 'á';
+        entities['226'] = 'â';
+        entities['227'] = 'ã';
+        entities['228'] = 'ä';
+        entities['229'] = 'å';
+        entities['230'] = 'æ';
+        entities['231'] = 'ç';
+        entities['232'] = 'è';
+        entities['233'] = 'é';
+        entities['234'] = 'ê';
+        entities['235'] = 'ë';
+        entities['236'] = 'ì';
+        entities['237'] = 'í';
+        entities['238'] = 'î';
+        entities['239'] = 'ï';
+        entities['240'] = 'ð';
+        entities['241'] = 'ñ';
+        entities['242'] = 'ò';
+        entities['243'] = 'ó';
+        entities['244'] = 'ô';
+        entities['245'] = 'õ';
+        entities['246'] = 'ö';
+        entities['247'] = '÷';
+        entities['248'] = 'ø';
+        entities['249'] = 'ù';
+        entities['250'] = 'ú';
+        entities['251'] = 'û';
+        entities['252'] = 'ü';
+        entities['253'] = 'ý';
+        entities['254'] = 'þ';
+        entities['255'] = 'ÿ';
+    }
+
+    if (useQuoteStyle !== 'ENT_NOQUOTES') {
+        entities['34'] = '"';
+    }
+    if (useQuoteStyle === 'ENT_QUOTES') {
+        entities['39'] = ''';
+    }
+    entities['60'] = '<';
+    entities['62'] = '>';
+
+
+    // ascii decimals to real symbols
+    for (decimal in entities) {
+        symbol = String.fromCharCode(decimal);
+        hash_map[symbol] = entities[decimal];
+    }
+
+    return hash_map;
+}
+
+/** Taken from php.js **/
+function html_entity_decode (string, quote_style) {
+
+    var hash_map = {},
+        symbol = '',
+        tmp_str = '',
+        entity = '';
+    tmp_str = string.toString();
+
+    if (false === (hash_map = this.get_html_translation_table('HTML_ENTITIES', quote_style))) {
+        return false;
+    }
+
+    delete(hash_map['&']);
+    hash_map['&'] = '&';
+
+    for (symbol in hash_map) {
+        entity = hash_map[symbol];
+        tmp_str = tmp_str.split(entity).join(symbol);
+    }
+    tmp_str = tmp_str.split(''').join("'");
+
+    return tmp_str;
+}
+
 const DBus = imports.dbus;
 const GLib = imports.gi.GLib;
 const Lang = imports.lang;
@@ -54,7 +224,8 @@ function PidginNotification(source) {
 
 function _fixText(text) {
     // remove all tags
-    let _text = text.replace(/<\/?[^>]+(>|$)/g, "");
+    let _text = html_entity_decode(text.replace(/<\/?[^>]+(>|$)/g, ""));
+    _text = _text.replace('&apos;', '\''); // Gets past html_entity_decode somehow.
     return _text;
 }