diff -r 000000000000 -r 6474c204b198 browser/locales/filter.py
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/browser/locales/filter.py	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,42 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+def test(mod, path, entity = None):
+  import re
+  # ignore anything but Firefox
+  if mod not in ("netwerk", "dom", "toolkit", "security/manager",
+                 "browser", "browser/metro", "webapprt",
+                 "extensions/reporter", "extensions/spellcheck",
+                 "other-licenses/branding/firefox",
+                 "browser/branding/official",
+                 "services/sync"):
+    return "ignore"
+  if mod not in ("browser", "browser/metro", "extensions/spellcheck"):
+    # we only have exceptions for browser, metro and extensions/spellcheck
+    return "error"
+  if not entity:
+    # the only files to ignore are spell checkers and search
+    if mod == "extensions/spellcheck":
+      return "ignore"
+    # browser
+    return "ignore" if re.match(r"searchplugins\/.+\.xml", path) else "error"
+  if mod == "extensions/spellcheck":
+    # l10n ships en-US dictionary or something, do compare
+    return "error"
+  if path == "defines.inc":
+    return "ignore" if entity == "MOZ_LANGPACK_CONTRIBUTORS" else "error"
+
+  if mod == "browser" and path == "chrome/browser-region/region.properties":
+    # only region.properties exceptions remain, compare all others
+    return ("ignore"
+            if (re.match(r"browser\.search\.order\.[1-9]", entity) or
+                re.match(r"browser\.contentHandlers\.types\.[0-5]", entity) or
+                re.match(r"gecko\.handlerService\.schemes\.", entity) or
+                re.match(r"gecko\.handlerService\.defaultHandlersVersion", entity))
+            else "error")
+  if mod == "browser/metro" and path == "chrome/region.properties":
+      return ("ignore"
+              if re.match(r"browser\.search\.order\.[1-9]", entity)
+              else "error")
+  return "error"