... frame/paragraph backgrounds.

If a style is set to have draw:fill="solid" and a derived style to
draw:fill="none" then the derived one must have
fo:background-color="transparent" to override the parent for old
consumers like LO <= 4.3/AOO <= 4.1 that don't understand draw:fill.

Change-Id: I5b56c7ace927338239195c6bfcfef1950544c8d2