port Yann's multiple-select implementation to cryptpad

www/form/index.html

@@ -63,6 +63,13 @@
             <option value="four">Four</option>
         </select> Dropdowns<br>
 
+        <select name="select-multiple" multiple>
+            <option value="pew">Pew</option>
+            <option value="bang">Bang</option>
+            <option value="kapow">Kapow</option>
+            <option value="zing">Zing</option>
+        </select>
+
         <textarea name="textarea"></textarea><br>
 
     </form>

www/form/main.js

@@ -91,7 +91,7 @@ define([
                 return function (content) {
                     return typeof content !== 'undefined' ?
                         $this.val(content):
-                        canonicalize($this.val());
+                        typeof($this.val()) === 'string'? canonicalize($this.val()): $this.val();
                 };
             }
         }());

www/form/ula.js

@@ -17,6 +17,7 @@ define([], function () {
         number: 'change',
         range: 'keyup change',
         'select-one': 'change',
+        'select-multiple': 'change',
         textarea: 'change keyup',
     };