[gtk] (6 commits) Non-fast-forward update to branch matthiasc/for-master

[Matthias Clasen <matthiasc src gnome org>]

The branch 'matthiasc/for-master' 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:

  f4df38a... contentserializer: Fix an annotation
  a3464c2... contentprovider: cosmetic fix
  dbe6fe1... wayland: Fix dnd type negotiation
  c9bc34d... dnd: Be safer

Commits added to the branch:

  662bcb3... Updated Spanish translation (*)
  21708e4... contentserializer: Fix an annotation (*)
  1841ec4... contentprovider: cosmetic fix (*)
  4b81849... wayland: Fix dnd type negotiation (*)
  e02fd80... dnd: Be safer (*)
  f7f06f8... stackswitcher: Fix switch-while-drag functionality

(*) This commit already existed in another branch; no separate mail sent