[gtksourceview] Non-fast-forward update to branch wip/fix-styles

[Sébastien Wilmet <swilmet src gnome org>]

The branch 'wip/fix-styles' was changed in a way that was not a fast-forward update.
NOTE: This may cause problems for people pulling from the branch. For more information,
please see:

 https://wiki.gnome.org/Git/Help/NonFastForward

Commits removed from the branch:

  efc7e19... Fix the 'classic' style scheme with dark gtk theme

Commits added to the branch:

  6e6e52c... Fix the style schemes when used with a dark gtk+ theme