Fix "Take Me Back" when ad-blocker enabled (#746)
Fix "Take Me Back" when ad-blocker enabled (#746)

When AdBlock is enabled, it prevents the ga script from executing
the hitCallback, required to actually navigate back to the classic
Polymer Elements catalog.

This patch follows the Google Analytics guide recommendation of
using setTimeout() to ensure the execution of the ga callback.
https://developers.google.com/analytics/devguides/collection/analyticsjs/sending-hits#handling_timeouts

Fixes #728
webcomponents/webcomponents.org,andymutton/beta,webcomponents/webcomponents.org,customelements/v2,customelements/v2,andymutton/beta,andymutton/v2,webcomponents/webcomponents.org,customelements/v2,andymutton/beta,andymutton/v2,andymutton/beta,andymutton/v2,customelements/v2,andymutton/v2