textlayout: fix bounds for clipping

This should match gtk_snapshot_append_layout(), which means that we expect the
bounds to be rooted at 0, 0.
5 jobs for wip/chergert/fix-textlayout-bounds in 5 minutes and 49 seconds (queued for 1 second)
Status Job ID Name Coverage
  Build
passed #362965
fedora-x86_64

00:03:30

passed #362966
win32
msys2-mingw32

00:05:49

 
  Flatpak
manual #362967
allowed to fail manual
flatpak-manual:demo
manual #362969
allowed to fail manual
flatpak-manual:icon-browser
manual #362968
allowed to fail manual
flatpak-manual:widget-factory