[gtk] (10 commits) ...Merge branch 'matthiasc/for-master' into 'master'

[Matthias Clasen <matthiasc src gnome org>]

Summary of changes:

  86aa011... Adwaita: Use child selectors in many more places (*)
  9eadcd8... testsuite: Update mark names (*)
  7e4feb0... colorbutton: Use a css name (*)
  da5d524... css: Print selectors (*)
  00be314... Adwaita: Drop menuitem support (*)
  975fe76... Adwaita: Remove a wildcard rule for tooltips (*)
  5dcce0c... css: Print out relative costs of selectors (*)
  55d08d8... Adwaita: Drop menu remnants (*)
  871959c... Adwaita: Drop selection mode (*)
  16654ee... Merge branch 'matthiasc/for-master' into 'master'

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