Remove out of date comments in EllipsisBox

Remove out of date comments relating to text directionality in
EllipsisBox.cpp. As of r165174 RenderBlockFlow::constructTextRun will
resolve the direction unless specified.

TBR=dglazkov@chromium.org
BUG=

Review URL: https://codereview.chromium.org/174383002

git-svn-id: svn://svn.chromium.org/blink/trunk@167546 bbb929c8-8fbe-4397-9dbb-9b2b20218538