CSSTUDIO-3337 Replace "instanceof VType" with "!= null".

Author: abrahamwolk

app/display/representation-javafx/src/main/java/org/csstudio/display/builder/representation/javafx/widgets/RegionBaseRepresentation.java

@@ -266,7 +266,7 @@ private void connectionOrValueChanged(final WidgetProperty<?> property, final Ob
                 if (alarm != null  &&  alarm.getSeverity() != AlarmSeverity.NONE)
                     // Have alarm info
                     severity = alarm.getSeverity();
-                else if (value instanceof VType)
+                else if (value != null)
                     // VType that doesn't provide alarm, always OK
                     severity = AlarmSeverity.NONE;
                 else // null