This way LogicalFontInstance can just be constructed by a
PhysicalFontFace based factory.

The patch also drops the wrong "Java logical font" comment
added by commit 125cdf34.

Change-Id: Ibd5d7da0c3a65dbfa2c8ae6b05cf616d39b749f2
Reviewed-on: https://gerrit.libreoffice.org/46475Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Jan-Marek Glogowski <glogow@fbihome.de>