Bug 1817727 - Disable test_filename_sanitize.js on mac because of...

Bug 1817727 - Disable test_filename_sanitize.js on mac because of permafailures. r=aryx, a=test-only

uriloader/exthandler/tests/unit/xpcshell.ini

@@ -16,6 +16,8 @@ skip-if =
     os == "android"
     appname == "thunderbird"
 [test_filename_sanitize.js]
+skip-if =
+  os == 'mac' # Bug 1817727
 [test_getFromTypeAndExtension.js]
 [test_getMIMEInfo_pdf.js]
 [test_getMIMEInfo_unknown_mime_type.js]