QmlDesigner.PropertyEdior: Fixing ComboBox

If there is no enum value fall back to the instanced value.

Change-Id: Idd4654d6e9fb8d4afd3df0855861511bc06454c1
Reviewed-by: Alessandro Portale <alessandro.portale@digia.com>

share/qtcreator/qmldesigner/propertyEditorQmlSources/HelperWidgets/ComboBox.qml

@@ -43,7 +43,10 @@ Controls.ComboBox {
         id: colorLogic
         backendValue: comboBox.backendValue
         onValueFromBackendChanged: {
-            comboBox.currentIndex = comboBox.find(comboBox.backendValue.enumeration);
+            var enumString = comboBox.backendValue.enumeration;
+            if (enumString === "")
+                enumString = comboBox.backendValue.value
+            comboBox.currentIndex = comboBox.find(enumString);
         }
     }