Repaint issues with vertical text which has absolute (or fixed) position specified for it.

For a writing mode root editable box which is absolute (or fixed) positioned
and which contains vertically aligned text within, trying to either insert
a paragraph in-between the text or trying to select part of the text does
not visually manifest the expected behavior.
An extra repaint is required to demonstrate the expected behavior.

This occurs because the repaint rect being computed in case of absolutely or
fixed positioned writing mode editable roots is not flipping the rect as per
the writing mode.

Removed the extra condition check for writing mode root box that flipped the
computed rect (based on the writing mode) only if the renderer was not absolute (or fixed) positioned.

R=leviw@chromium.org,eseidel@chromium.org,ojan@chromium.org
BUG=259352, 230580

Review URL: https://codereview.chromium.org/18254006

git-svn-id: svn://svn.chromium.org/blink/trunk@177870 bbb929c8-8fbe-4397-9dbb-9b2b20218538