[discourse-web] brotli is actually needed by init-assets.sh

[Andrea Veri <averi src gnome org>]

commit 9dfd9035dac966c2632d1b24d24ca0d065bb230f
Author: Andrea Veri <averi redhat com>
Date:   Fri Apr 26 14:20:50 2019 +0200

    brotli is actually needed by init-assets.sh

 Dockerfile | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)
---
diff --git a/Dockerfile b/Dockerfile
index 50fa036..69c1540 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -14,7 +14,9 @@ RUN apt update && \
     # Install image utilities
     advancecomp jpegoptim gifsicle libjpeg-turbo-progs libpng-dev optipng pngcrush pngquant jhead gsfonts \
     # Install nodejs and npm
-    nodejs && \
+    nodejs \
+    # Needed by init-assets.sh
+    brotli && \
     # Fix https://meta.discourse.org/t/uglifier-error-during-assets-precompile/96970
     npm install -g uglify-js@"<3" && \
     # Install svgo