Disable test_plugin_freezing.html for now since it causes focus problems

--HG--
extra : rebase_source : 5d2a0e81b7c39993a666b6dc4841ae1ba0097dac

content/base/test/Makefile.in

@@ -309,8 +309,9 @@ _TEST_FILES = 	test_bug5141.html \
 		test_bug466751.xhtml \
 		test_bug461555.html \
 		test_sync_xhr_timer.xhtml \
-		test_plugin_freezing.html \
 		$(NULL)
+# Disabled; see bug 492181
+#		test_plugin_freezing.html
 
 # Disabled for now. Mochitest isn't reliable enough for these.
 # test_bug444546.html \