[gtk] (9 commits) Non-fast-forward update to branch wip/ebassi/constraint-layout

[Emmanuele Bassi <ebassi src gnome org>]

The branch 'wip/ebassi/constraint-layout' 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:

  cb11ba4... Fix the opposite size measurement in GtkConstraintLayout
  7afac64... Notify a layout change when adding and removing constraints
  02f4e1a... Add GtkConstraintTarget
  3a8c1ab... widget: Implement GtkConstraintTarget
  8f5515d... Redefine constraints with GtkConstraintTarget
  8bacf47... Use generic pointers for constraint targets
  4efcad5... Add GtkConstraintGuide
  04d7e89... Make the constraints demo more interesting
  cf702b8... Add an interactive constraints demo

Commits added to the branch:

  e4466dd... Fix the opposite size measurement in GtkConstraintLayout
  c81e047... Notify a layout change when adding and removing constraints
  4de3e99... Add GtkConstraintTarget
  4b11e73... widget: Implement GtkConstraintTarget
  f8647b0... Redefine constraints with GtkConstraintTarget
  20c4a4b... Use generic pointers for constraint targets
  ffd8b19... Add GtkConstraintGuide
  fc3f4aa... Make the constraints demo more interesting
  12d45c0... Add an interactive constraints demo