squeezer: Use the CSS sizing helpers

This makes it take CSS size properties into account.

Fixes GNOME/libhandy#229
11 jobs for squeezer-margin in 21 minutes and 2 seconds (queued for 1 second)
Status Name Job ID Coverage
  Build
passed api-visibility #844158

00:00:17

passed build-debian-clang #844160

00:03:02

passed build-debian-gcc #844159

00:05:16

passed build-fedora-gcc #844161

00:12:26

passed build-flatpak #844162
flatpak

00:01:46

passed build-flatpak-glade #844163
flatpak

00:04:18

 
  Test+Docs
passed build-gtkdoc #844164

00:03:07

passed unit-test #844165

00:03:15

44.1%
 
  Package
passed package-debian-buster #844166

00:02:56

 
  Test Package
passed autopkgtest-debian-buster-package #844167

00:02:19

passed lintian-debian-buster-package #844168

00:00:51