Fix hyphen color in selected text.

Text with selection is painted in 3 steps:
1) Background painting.
2) Not selected text is painted with regular color. If ePos does not consider
hyphen, then "-" is painted at this step.
3) Selected text is painted with color of selection. If ePos does not consider
hyphen, then "-" is not painted at this step.
As result we have incorrect color for hyphen symbol.

This commit updates ePos with respect of hyphen.

R=abarth@chromium.org,zimmermann@kde.org,eseidel@chromium.org

BUG=388217

Review URL: https://codereview.chromium.org/356473005

git-svn-id: svn://svn.chromium.org/blink/trunk@180810 bbb929c8-8fbe-4397-9dbb-9b2b20218538