Use-after-free in actor-layout test
The actor-layout test intermittently crashes for me. Valgrind says there's a use-after-free:
==16487== Invalid read of size 8
==16487== at 0x4A03DE4: clutter_master_clock_gdk_update (clutter-master-clock-gdk.c:282)
==16487== by 0x4978EB1: g_closure_invoke (gclosure.c:810)
==16487== by 0x498C3B3: signal_emit_unlocked_R (gsignal.c:3635)
==16487== by 0x499510E: g_signal_emit_valist (gsignal.c:3391)
==16487== by 0x499579E: g_signal_emit (gsignal.c:3447)
==16487== by 0x50C517A: gdk_frame_clock_paint_idle (gdkframeclockidle.c:450)
==16487== by 0x50AFD27: gdk_threads_dispatch (gdk.c:777)
==16487== by 0x4893293: g_timeout_dispatch (gmain.c:4678)
==16487== by 0x48927EE: g_main_dispatch (gmain.c:3189)
==16487== by 0x48927EE: g_main_context_dispatch (gmain.c:3854)
==16487== by 0x4892BBF: g_main_context_iterate.isra.0 (gmain.c:3927)
==16487== by 0x4892C4E: g_main_context_iteration (gmain.c:3988)
==16487== by 0x4A6FC13: clutter_test_check_actor_at_point (clutter-test-utils.c:385)
==16487== Address 0xe436b68 is 8 bytes inside a block of size 24 free'd
==16487== at 0x48369AB: free (vg_replace_malloc.c:540)
==16487== by 0x48B0CF9: g_slice_free_chain_with_offset (gslice.c:1231)
==16487== by 0x4978EB1: g_closure_invoke (gclosure.c:810)
==16487== by 0x498C3B3: signal_emit_unlocked_R (gsignal.c:3635)
==16487== by 0x499510E: g_signal_emit_valist (gsignal.c:3391)
==16487== by 0x499579E: g_signal_emit (gsignal.c:3447)
==16487== by 0x497D533: g_object_dispatch_properties_changed (gobject.c:1088)
==16487== by 0x497CE1D: g_object_notify_queue_thaw (gobject.c:296)
==16487== by 0x497FB0A: g_object_thaw_notify (gobject.c:1325)
==16487== by 0x4A6F7A7: validate_stage (clutter-test-utils.c:311)
==16487== by 0x4A54611: _clutter_run_repaint_functions (clutter-main.c:3449)
==16487== by 0x4A03DA5: master_clock_update_stage (clutter-master-clock-gdk.c:251)
==16487== by 0x4A03DA5: clutter_master_clock_gdk_update (clutter-master-clock-gdk.c:306)
==16487== Block was alloc'd at
==16487== at 0x483577F: malloc (vg_replace_malloc.c:309)
==16487== by 0x48983F8: g_malloc (gmem.c:99)
==16487== by 0x48B00E1: g_slice_alloc (gslice.c:1024)
==16487== by 0x488EA83: g_list_append (glist.c:264)
==16487== by 0x4A03A54: clutter_master_clock_gdk_add_stage_clock (clutter-master-clock-gdk.c:378)
==16487== by 0x4A03A54: clutter_master_clock_gdk_listen_to_stage (clutter-master-clock-gdk.c:425)
==16487== by 0x4A03A54: clutter_master_clock_gdk_stage_visibility (clutter-master-clock-gdk.c:435)
==16487== by 0x4A03B8D: clutter_master_clock_gdk_init (clutter-master-clock-gdk.c:523)
==16487== by 0x499BDEC: g_type_create_instance (gtype.c:1864)
==16487== by 0x497E70C: g_object_new_internal (gobject.c:1805)
==16487== by 0x497FE1C: g_object_new_with_properties (gobject.c:1973)
==16487== by 0x4980870: g_object_new (gobject.c:1645)
==16487== by 0x4A54E0A: _clutter_master_clock_get_default (clutter-master-clock.c:69)
==16487== by 0x4A6C264: _clutter_stage_queue_event (clutter-stage.c:923)