Fix "null" instead of empty string on messages list in IE10 (#1489145)

CHANGELOG

@@ -1,6 +1,7 @@
 CHANGELOG Roundcube Webmail
 ===========================
 
+- Fix "null" instead of empty string on messages list in IE10 (#1489145)
 - Fix so bounces addresses in Sender headers are skipped on Reply-All (#1489011)
 - Fix bug where serialized strings were truncated in PDO::quote() (#1489142)
 - Fix displaying messages with invalid self-closing HTML tags (#1489137)

program/js/app.js

@@ -1892,6 +1892,7 @@ function rcube_webmail()
       else
         html = cols[c];
 
+      if (html)
         col.innerHTML = html;
 
       row.appendChild(col);
@@ -4417,6 +4418,7 @@ function rcube_webmail()
     for (c in cols) {
       col = document.createElement('td');
       col.className = String(c).toLowerCase();
+      if (cols[c])
         col.innerHTML = cols[c];
       row.appendChild(col);
     }
@@ -5863,7 +5865,7 @@ function rcube_webmail()
 
         for (c=0, len=repl.length; c < len; c++) {
           cell = document.createElement('td');
-          cell.innerHTML = repl[c].html;
+          cell.innerHTML = repl[c].html || '';
           if (repl[c].id) cell.id = repl[c].id;
           if (repl[c].className) cell.className = repl[c].className;
           tr.appendChild(cell);