Bug 1669007. Set the pref gfx.font_loader.delay=0 when running reftests in layout/general/test to fix test_scroll_position_restore.html intermittent failure. r=jfkthame

Differential Revision: https://phabricator.services.mozilla.com/D94694

layout/generic/test/mochitest.ini

@@ -1,6 +1,7 @@
 [DEFAULT]
 prefs =
   plugin.load_flash_only=false
+  gfx.font_loader.delay=0
 skip-if = toolkit == 'android' #CRASH_DUMP, RANDOM, ONLY IN CHUNK 10
 support-files =
   ../../reftests/backgrounds/blue-32x32.png