Bug 1377068 - temporarily disable layout/style/test/test_variables.html. r=xidorn

--HG--
extra : rebase_source : 09e142143bf188f3ae896d3dfee2ec3db72f8b66

layout/style/test/mochitest.ini

@@ -314,6 +314,7 @@ skip-if = toolkit == 'android'
 [test_variable_serialization_computed.html]
 [test_variable_serialization_specified.html]
 [test_variables.html]
+skip-if = stylo # bug 1375555
 support-files = support/external-variable-url.css
 [test_video_object_fit.html]
 [test_viewport_scrollbar_causing_reflow.html]