Ensure there's always a listener on VUI for closing tooltips (#11051)

Change-Id: I04e8b1777bc4bf4f64371e4b6e6d77f3754162ad

client/src/com/vaadin/client/ui/ui/UIConnector.java

@@ -44,6 +44,7 @@ import com.vaadin.client.ConnectorHierarchyChangeEvent;
 import com.vaadin.client.ConnectorMap;
 import com.vaadin.client.Focusable;
 import com.vaadin.client.Paintable;
+import com.vaadin.client.TooltipInfo;
 import com.vaadin.client.UIDL;
 import com.vaadin.client.VConsole;
 import com.vaadin.client.communication.StateChangeEvent;
@@ -473,6 +474,16 @@ public class UIConnector extends AbstractSingleComponentContainerConnector
         }
     }
 
+    @Override
+    public TooltipInfo getTooltipInfo(com.google.gwt.dom.client.Element element) {
+        /*
+         * Override method to make AbstractComponentConnector.hasTooltip()
+         * return true so there's a top level handler that takes care of hiding
+         * tooltips whenever the mouse is moved somewhere else.
+         */
+        return super.getTooltipInfo(element);
+    }
+
     /**
      * Tries to scroll the viewport so that the given connector is in view.
      *