SearchAction proposals inconsistently populated on iOS

The `SearchAction` proposal liste is inconsistently populated when an empty search string is applied. The effect can be seen in the [search action snippet](https://github.com/eclipsesource/tabris-js/blob/master/snippets/action-search/search-action.js):
1. Open the app
2. Hit SearchAction -> search ui opens with list of all proposals (correct)
3. Type L -> search list is filered
4. Delete the L -> search list shows all proposals
5. Close search ui
6. Hit Search Action -> Proposal list is empty although it should show all propsals