bugfix: Avoid possible duplicate declaration of sib-display

While testing the Hubl app on the 0.10 version of core I got an error with duplicate declaration of sib-display.

It is because in our defineComponent method we dit not use the same customElements.get(x) check on the sib-* prefixed components as we do for the newly solid-* component name.

So I just replicated the check to ensure the component declaration is not run twice, especially when the core is embedded by components.