Bug 1388764 - Skip test_object_plugin_nav.html on Linux debug builds for frequent mozilla::ipc::MessageChannel::WillDestroyCurrentMessageLoop() shutdown crashes. r=qdot

dom/html/test/mochitest.ini

@@ -502,7 +502,7 @@ skip-if = toolkit == 'android' # bug 939642
 [test_nested_invalid_fieldsets.html]
 [test_object_attributes_reflection.html]
 [test_object_plugin_nav.html]
-skip-if = (toolkit == 'android') || (os == 'win' && debug) # plugins not supported on android, bug 1388764 for debug
+skip-if = (toolkit == 'android') || ((os == 'win' || os == 'linux') && debug) # plugins not supported on android, bug 1388764 for debug
 [test_ol_attributes_reflection.html]
 [test_option_defaultSelected.html]
 [test_option_selected_state.html]