For one, aPos.Y() is meant to be the baseline position of the text.
Based on the MSDN documentation and
<https://www-user.tu-chemnitz.de/~ygu/petzold/ch05c.htm>, that means if
we want to get top position, we have to only extract tmAscent and not
tmInternalLeading.

For another, ImplWinFontEntry::AddChunkOfGlyphs() adds a border of 2
pixels both horizontally and vertically, which means that then we need
to undo that when counting the vertical position, too.

Change-Id: I4ac8e881ea5910662674c2a1b53ece943487ccd9