Since the margin collapsing (aka contextual spacing, implemented
for LO 3.6 by Miklos Vajna, commits
6f04bf5e,
0662778b,
11059331,
03f9b6be,
8631dbf8,
9f4bb5bd,
f722299e) is only meant
to suppress fo:margin-top and fo:margin-bottom, as seen in
https://issues.oasis-open.org/browse/OFFICE-3767, current
implementation is inconsistent: it nullifies all spacing, including
normal line spacing.

This patch makes sure that collapsing conforms to specification.

Change-Id: I413f6469d7891dd85f1f7a2c666f219187ddaec4
Reviewed-on: https://gerrit.libreoffice.org/28692Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Miklos Vajna <vmiklos@collabora.co.uk>