Bug 1423218 - Disable a11y test_tabbrowser.xul in Windows coverage builds. r=jmaher

--HG--
extra : rebase_source : 9d0215e31081c77fa1dd993f4dc32b0876e70ab3

accessible/tests/mochitest/tree/a11y.ini

@@ -45,7 +45,7 @@ skip-if = buildapp == "mulet"
 [test_select.html]
 [test_tabbox.xul]
 [test_tabbrowser.xul]
-skip-if = os == 'linux' && debug # Bug 1389365
+skip-if = (os == 'linux' && debug) || (os == 'win' && ccov) # Bug 1389365 || bug 1423218
 [test_table.html]
 [test_tree.xul]
 [test_txtcntr.html]