[gtk/matthiasc/for-master] (8 commits) ...window: Remove some dead code

[Matthias Clasen <matthiasc src gnome org>]

Summary of changes:

  739137c... clipboard: GdkContentProviderUnion should return after writ (*)
  7df572d... gsk: Add GskTransform autocleanup definition (*)
  2cc6c4d... csswidgetnode: Don't check for container (*)
  0e25190... Merge branch 'matthiasc/for-master' into 'master' (*)
  61d39a0... Merge branch 'gbsneto/css-dequeue-fix' into 'master' (*)
  20f1604... Merge branch 'tintou/gsk-transform-autocleanup' into 'maste (*)
  53ca60a... Merge branch 'carlosgc/content-provider-union-write' into ' (*)
  91a84fe... window: Remove some dead code

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