Change const to var for IE8 support.
Added Object.create shim for existing inheritance to support IE8.
Replaced Object.keys.forEach with for-in loop to support IE8.
Changed Array.indexOf to loop to support IE8.
Cleaned up linting issues
Change textContent to innerHTML to support IE8.

The tests are breaking for me so I can't tell if this is a breaking change, but it looked like it might not be. textContent works like innerHTML execept it basically strips out the tags. It looke like the nodes were already text nodes, so this shouldn't be an issue.
Uncatching an error to not hide issues
Changed object.create function to not affect the global Object.create
Fix small linting issue.
Change textContent fix for IE8 to use innerText.

'innerHTML' won't work in this case as some of the nodes
we're working with can be text nodes which don't support
'innerHTML'. Instead we can use 'innerText' if
'textContent' does not exist on the node as IE8/7 support
this method.