[gtk] (4 commits) Non-fast-forward update to branch improve-css-test-4.6

[Matthias Clasen <matthiasc src gnome org>]

The branch 'improve-css-test-4.6' 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:

  a3731c2... css: Propagate charset conversion errors
  746f3fb... tests: Check the error first

Commits added to the branch:

  9d01189... gtkscrolledwindow: Backport scroll speed from 4.7/main (*)
  e93a547... Merge branch 'wip/carlosg/scroll-speed-4-6' into 'gtk-4-6' (*)
  ac18330... css: Propagate charset conversion errors
  6b019d4... tests: Check the error first

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