Renamed function name & reorder args for clarity + added docs.

* Renamed buildDOMFragmentForTokenStream --> buildDOMFragmentTokens
  and made env. the first arg.

* Added documentation to buildDOMFragmentTokens and encapsulateHTML

Change-Id: I7eccfd3f4dc5b4b91d20d1d24d98ec514df6dfbc
Merge "Renamed function name & reorder args for clarity + added docs."