Windows: Use GrayText for disabled selected <option>.

Aura uses lighter gray for the background of inactive selection. So
the default color defined in html.css.

Note: The pixel result of listbox-appearance-basic.html looks worse
because we use darker gray for the background of inactive selection in
layout tests.

BUG=339316
TEST=automated
R=keishi@chromium.org

Review URL: https://codereview.chromium.org/149273006

git-svn-id: svn://svn.chromium.org/blink/trunk@166190 bbb929c8-8fbe-4397-9dbb-9b2b20218538