Simplify use of TextDirection enum.

There is no need to do "(m_direction == LTR) ? LTR : RTL".

While here, remove extra parameters from applyFontTransforms.

Review URL: https://codereview.chromium.org/330063005

git-svn-id: svn://svn.chromium.org/blink/trunk@176522 bbb929c8-8fbe-4397-9dbb-9b2b20218538