Remove the fulltext "reconstructDocument()" method

Summary: Ref T12819. This was originally intended for debugging, but never actually used and not clearly useful. There are no callers and it probably does not work. Just get rid of it.

Test Plan: Grepped for callers; none exist.

Reviewers: chad

Reviewed By: chad

Maniphest Tasks: T12819

Differential Revision: https://secure.phabricator.com/D18544