[OpenJDK 2D-Dev] RFR: 8158408: Font2DTest demo needs to use FontPanel resolution matching the screen

[Philip Race]

Bug: https://bugs.openjdk.java.net/browse/JDK-8158408
Webrev: http://cr.openjdk.java.net/~prr/8158408/

At 125% scaling on JDK 9 Font2DTest looks horrid since its
BufferedImage is scaled to the screen.
Fix is to not use a BufferedImage, just use the Swing back buffer.

-phil.