Win Safari does not respond to High Contrast mode. To enter High Contrast mode: Start, Settings, Control Panel, Accessibility Options, Display, High Contrast tab, Use High Contrast checkbox. (I used a setting of "High Contrast Black".)
This seems to be a part WebCore, part Safari bug, so a radar should be filed for the Safari half. For the WebCore side, we could probably do a lot of the required work with a custom user agent stylesheet.
<rdar://problem/5653319>
I can confirm this bug in the latest Webkit r30236 for Windows. However, if the bug exists only in Safari part, not in Webkit, please close the bug as INVALID.
No longer relevant. See also the new standard `@media (prefers-contrast: more)`