Mark a couple of complex text tests as needing manual rebaseline

Mark a couple of complex text tests needing manual rebaseline as they
will change slightly (<1px) with the new harfbuzz version.

BUG=318953
TBR=leviw@chromium.org

Review URL: https://codereview.chromium.org/68133015

git-svn-id: svn://svn.chromium.org/blink/trunk@161956 bbb929c8-8fbe-4397-9dbb-9b2b20218538