code: function byIdRef(id, ref) {
        var cmp = this.byId(id).lookupReferenceHolder(false).lookupReference(ref);
        if (!cmp) {
          throw new Error('Component not found for container id: ' + id + ', reference: ' + ref);
        }
        return cmp;
      }
docs: Gets component using id and reference.
  @param id - component HTML id.
  @param ref - reference inside component found by id.