css: crash in font features value
Seen while playing with css font features:
(gdb) bt
#0 0x00007ffff7aa8c1c in gtk_css_value_unref (value=0x1) at ../gtk/gtkcssvalue.c:179
#1 0x00007ffff75dd352 in g_hash_table_remove_all_nodes
(hash_table=0x15c8120, notify=<optimized out>, destruction=<optimized out>)
at ../glib/ghash.c:701
#2 0x00007ffff75de6ff in g_hash_table_remove_all_nodes
(destruction=1, notify=1, hash_table=0x15c8120) at ../glib/ghash.c:1452
#3 g_hash_table_unref (hash_table=0x15c8120) at ../glib/ghash.c:1452
#4 0x00007ffff7a7d1cd in gtk_css_value_font_features_free (value=0x64a380)
at ../gtk/gtkcssfontfeaturesvalue.c:48
#5 0x00007ffff7aa8c48 in gtk_css_value_unref (value=0x64a380)
at ../gtk/gtkcssvalue.c:192
#6 0x00007ffff7810861 in gtk_css_ruleset_clear (ruleset=0xcffa00)
at ../gtk/gtkcssprovider.c:250
#7 0x00007ffff78113c7 in gtk_css_provider_reset
(css_provider=0x1444680 [GtkCssProvider]) at ../gtk/gtkcssprovider.c:598
#8 0x00007ffff7812527 in gtk_css_provider_load_from_data
(css_provider=0x1444680 [GtkCssProvider], data=0x1b7bf20 "text {\n font-feature-settings: \"tnum \" on;\n}", length=45) at ../gtk/gtkcssprovider.c:1105
#9 0x00007ffff7b1a18c in update_style (ce=0x14393d0 [GtkInspectorCssEditor])
at ../gtk/inspector/css-editor.c:267
#10 0x00007ffff7b1a1d6 in update_timeout (data=0x14393d0,
data@entry=<error reading variable: value has been optimized out>)
at ../gtk/inspector/css-editor.c:279
#11 0x00007ffff75f0e74 in g_timeout_dispatch
(source=0x150a0d0, callback=<optimized out>, user_data=<optimized out>)
at ../glib/gmain.c:4841
#12 0x00007ffff75f02d0 in g_main_dispatch (context=0x457830) at ../glib/gmain.c:3346
#13 g_main_context_dispatch (context=context@entry=0x457830) at ../glib/gmain.c:4015
#14 0x00007ffff75f06b0 in g_main_context_iterate
(context=context@entry=0x457830, block=block@entry=1, dispatch=dispatch@entry=1, self=<optimized out>) at ../glib/gmain.c:4088
#15 0x00007ffff75f073f in g_main_context_iteration
(context=context@entry=0x457830, may_block=may_block@entry=1)
at ../glib/gmain.c:4149
#16 0x00007ffff7446ead in g_application_run
(application=0x4481b0 [GtkApplication], argc=<optimized out>, argv=<optimized out>) at ../gio/gapplication.c:2559
#17 0x000000000040d3f7 in main (argc=1, argv=0x7fffffffe198)
at ../demos/widget-factory/widget-factory.c:2094