Improve the Promise subclass example test

Fixes a few common causes of error:

* Yahoo! is now Yahoo with no exclamation mark :poultry_leg: 
* Changes the poll check to check the node for 10 children, rather than > 1.  This previously caused problems when the "Done!" nodes were not yet appended.

Improves clarity of the test:

* It's no longer comparing a giant blob of HTML.