Bug 534903: make branding always use en-US strings, since l10n branding directories haven't caught up (and aren't really necessary), r=Pike

mobile/branding/official/locales/jar.mn

@@ -2,5 +2,6 @@
 
 @AB_CD@.jar:
 % locale branding @AB_CD@ %locale/branding/
-  locale/branding/brand.dtd        (%brand.dtd)
-* locale/branding/brand.properties (%brand.properties)
+# Branding only exists in en-US
+  locale/branding/brand.dtd        (en-US/brand.dtd)
+* locale/branding/brand.properties (en-US/brand.properties)