Regression - Menu mgmt dialog does now show error message when external link is empty (Blur doesn't trigger on clicking a draggable item)

1. Login to CMS
2. Navigate to Channel Mgr >> Edit Channel >> Edit Menu
3. Select any menu (example Products)
4. Click on "Add Menu item"
5. Name the Label as "TestOne"
6. Select Destination as "External link"
7. Without filling URL, try switching to another menu

Expected - Error is shown that URL is invalid
Actual - Error is not shown

Suggestion - When internal links are left empty and user attempts to move away, still error should be shown.