If this class is used as a mixin, this method must be called from inside
of the created() constructor.
If this class is a superclass, calling super.created() is sufficient.
void polymerCreated() {
var t = nodeBind(this).templateInstance;
if (t != null && t.model != null) {
window.console.warn('Attributes on $_name were data bound '
'prior to Polymer upgrading the element. This may result in '
'incorrect binding types.');
}
prepareElement();
if (!isTemplateStagingDocument(ownerDocument)) {
_makeElementReady();
}
}