Direct2D QPA: Add missing break statement

Change-Id: Ib40daa1ba56cce423b29ac8f1ab50e4638980728
Reviewed-by: Risto Avila <risto.avila@digia.com>
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@digia.com>
Direct2D QPA: Fix HighRes painting

It turns out that supporting HighRes painting with Direct2D is quite
simple. Two things are necessary.

First, we set the unit mode to D2D1_UNIT_MODE_PIXELS on all our device
contexts, which tells Direct2D that we specify everything in pixels.
Direct2D will internally do the required conversions.

Second, we scale font sizes according to DPI.

Previously rendering errors resulted when a highres mode was used, this
fixes those errors.

Task-number: QTBUG-39105
Change-Id: Ibb4dbea4746687228249e2c36d48c4bd6c5c7bf9
Reviewed-by: Risto Avila <risto.avila@digia.com>
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@digia.com>