Chord symbols do not display in startup score if no custom default style specified

In https://github.com/musescore/MuseScore/commit/3380821548db16a872a02aa50… the treatment of the startup score (eg, the default untitled / My_First_Score) changed. Previously, we read it then applied baseStyle, presumably so everyone got the same generic score. We decided it would be nice if people saw their custom default style (if any) applied, so it made sense at the time to change the setStyle(baseStyle) to setStyle(defaultStyle). Unfortunately, if the default style was not customized, then there was never a call to MStyle::load() and thus no chord symbol list was ever built.

I think a) we don't need to call setStyle(defaultStyle), the score should already be at default style at that point (?), but also b) we should make sure defaultStyle has a chord list anyhow.

EDIT: I'm wrong about a), that's true only for new scores, not read scores.