build: Run unit tests on meson test

Meson makes it easy to define unit tests, so hook up the existing
ones.

https://bugzilla.gnome.org/show_bug.cgi?id=786497

tests/meson.build

@@ -1,8 +1,18 @@
 testconf = configuration_data()
 testconf.set('MUTTER_TYPELIB_DIR', mutter_typelibdir)
 testconf.set('srcdir', meson.current_source_dir())
-configure_file(
+run_test = configure_file(
   input: 'run-test.sh.in',
   output: 'run-test.sh',
   configuration: testconf
 )
+
+testenv = environment()
+testenv.set('GSETTINGS_SCHEMA_DIR', join_paths(meson.build_root(), 'data'))
+
+foreach test : ['insertSorted', 'jsParse', 'markup', 'url']
+  test(test, run_test,
+    args: 'unit/@0@.js'.format(test),
+    env: testenv,
+    workdir: meson.current_source_dir())
+endforeach