[Qt] Use same DPI for application font as rest of app in DRT and WTR

[Qt] Use same DPI for application font as rest of app in DRT and WTR

QApplication will initialize the default application font based
on the application DPI at construction time, but we then override
the application DPI using QX11Info (hard-coding it to 96 for
consistency). This hard-coding is not reflected in the application
font, so we explicitly have update the font ourselves.

The 6 test results that are updated were originally produced with
a DPI of 75, as this is the default fallback DPI when a QFont is
constructed before QApplication. This was wrong, and the results
are updated to match a DPI of 96.

Reviewed by Csaba Osztrogonác.

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@95729 268f45cc-cd09-0410-ab3c-d52691b4dbfc