Add tree-construction tests...

These tests cover encountering <template> in "in select in table", "after body" and "after head".

These tests have already been landed in blinks down-stream repo and are reflected in the whatwg spec.

-in select in table: http://www.whatwg.org/specs/web-apps/current-work/#reset-the-insertion-mode-appropriately (step 4)

-after body: http://www.whatwg.org/specs/web-apps/current-work/#parsing-main-afterbody ("anything else" defers to "in body"

-after head: http://www.whatwg.org/specs/web-apps/current-work/#reset-the-insertion-mode-appropriately (step 15.2)