When marking a line changed because of internal whitespace in "Ignore Most", intraline diff it

Summary:
Currently, we mark some lines that otherwise count as "unchanged" to be "changed" when they have internal whitespace changes.

However, we've already excluded them from the intra-line diff algorithm. Unset the flag so they can get intra-line diffed.

Test Plan: Viewed a change with internal whitespace changes, internal whitespace changes were intraline diffed.

Reviewers: btrahan

Reviewed By: btrahan

CC: aran, epriestley

Maniphest Tasks: T970

Differential Revision: https://secure.phabricator.com/D1871