fix(calendar): don't allow RDATE unless already defined

Since RDATE are not properly supported in EAS, hide the possibility to
specify recurring dates unless the component being edited already
contains RDATE(s).

UI/Templates/SchedulerUI/UIxTaskEditorTemplate.wox

@@ -196,9 +196,7 @@
             <md-input-container class="md-block md-flex">
               <label><var:string label:value="Repeat"/></label>
               <md-select ng-model="editor.component.repeat.frequency" ng-disabled="editor.component.occurrenceId">
-                <var:foreach list="repeatList" item="item">
-                  <md-option var:value="item"><var:string var:value="itemRepeatText"/></md-option>
-                </var:foreach>
+                <md-option ng-value="frequency[0]" ng-repeat="frequency in ::editor.frequencies()">{{ frequency[1] }}</md-option>
               </md-select>
             </md-input-container>
             <md-button type="button" class="sg-icon-button"