Fix PHP warning in html_table::set_row_attribs() in PHP 5.4 (#1489094)

CHANGELOG

@@ -1,6 +1,7 @@
 CHANGELOG Roundcube Webmail
 ===========================
 
+- Fix PHP warning in html_table::set_row_attribs() in PHP 5.4 (#1489094)
 - Fix invalid option selected in default_font selector when font is unset (#1489112)
 - Fix displaying contact with ID divisible by 100 in sql addressbook (#1489121)
 - Fix browser warnings on PDF plugin detection (#1489118)

program/lib/Roundcube/html.php

@@ -771,6 +771,11 @@ class html_table extends html
             $index = $this->rowindex;
         }
 
+        // make sure row object exists (#1489094)
+        if (!$this->rows[$index]) {
+            $this->rows[$index] = new stdClass;
+        }
+
         $this->rows[$index]->attrib = $attr;
     }