[chrome-gnome-shell] firefox: restrict maximum version to 53.

[Yuri Konotopov <ykonotopov src gnome org>]

commit 61816ae42a3a29f5b2c85ea6bbdf3fa7e9d5ca48
Author: Yuri Konotopov <ykonotopov gnome org>
Date:   Sun Mar 5 00:36:26 2017 +0400

    firefox: restrict maximum version to 53.
    
    runtime.onMessageExternal will be available in Firefox 54 so we should
    remove compat part prior to this release.

 extension/manifest.firefox.json |    3 ++-
 1 files changed, 2 insertions(+), 1 deletions(-)
---
diff --git a/extension/manifest.firefox.json b/extension/manifest.firefox.json
index 8111644..540dbbd 100644
--- a/extension/manifest.firefox.json
+++ b/extension/manifest.firefox.json
@@ -2,7 +2,8 @@
   "applications": {
     "gecko": {
       "id": "chrome-gnome-shell gnome org",
-      "strict_min_version": "52.0"
+      "strict_min_version": "52.0",
+      "strict_max_version": "53.*"
     }
   },
   "permissions": [