Fix an async display issue for tokenizer/typeahead results

Summary:
Ref T4420. After the changes to the tokenizer, I sometimes do this:

  - Type something like "diff" into a project typeahead.
  - Select "differential".
  - A fraction of a second later, the typeahead pops back open.

This is because I selected the result from a partial query (like "diff" running against the "di" results) and then the full results of the "diff" query came back to the browser.

Instead, when showing results, require that the current state match the state that the results are for: don't show "dog" results if the tokenizer now reads "cat", for whatever reason.

Test Plan: Added a 1s delay to results, typed "a", then typed "m" and selected a result in less than a second. Prior to the patch, the tokenizer would pop back open with "am" results afterward. Now, it doesn't.

Reviewers: btrahan, chad

Reviewed By: chad

CC: aran

Maniphest Tasks: T4420

Differential Revision: https://secure.phabricator.com/D8250