Bug 1076941 - Skip the toolkit webapps tests on OSX 10.8 due to frequent timeouts.

toolkit/webapps/tests/chrome.ini

@@ -1,5 +1,5 @@
 [DEFAULT]
-skip-if = buildapp == 'mulet' || os == "mac" && os_version == "10.6" # see bug 993690
+skip-if = buildapp == 'mulet' || os == "mac" # see bug 993690 and bug 1076941
 support-files =
   head.js
   app.sjs