[REVIEW 3-6][REVIEW 3-5] fdo#50285 superscript appears on .doc reload

[Caolán McNamara]

I broke this with b3cee382f449aa69213dc21f7b1ba6a5356d2865 to merge
on .doc load consecutive properties with the same value for performance,
but I didn't take into account intermediate character style properties.

Safest patch, other that getting rid of the optimization, is to only
merge if there are no intermediate properties. 

http://cgit.freedesktop.org/libreoffice/core/commit/?id=08ffb7bc5ec4472126762f4cb9677349b61122f6

C.