Support for HTML nodes

[Max9403]

While using https://github.com/googlemaps/js-markerclusterer we run into an issue with the call stack being exceeded since it's comparing 2 lists of google's custom HTML elements (<gmp-advanced-marker />). It most likely a cyclic issue that is happening. However, we managed to fix it by adding the below (as a quick patch before release):

  if (a instanceof Node) return a.isEqualNode(b);