DEV: Install evergreen Firefox in test image

DEV: Install evergreen Firefox in test image

diff --git a/image/discourse_test/Dockerfile b/image/discourse_test/Dockerfile
index b8cb62a..362fe90 100644
--- a/image/discourse_test/Dockerfile
+++ b/image/discourse_test/Dockerfile
@@ -22,6 +22,8 @@ RUN wget -q -O - https://dl-ssl.google.com/linux/linux_signing_key.pub | sudo ap
     apt update &&\
     apt install -y libgconf-2-4 libxss1 google-chrome-stable firefox-esr &&\
     npm install -g eslint babel-eslint &&\
+    cd /tmp && wget "https://download.mozilla.org/?product=firefox-latest-ssl&os=linux64&lang=en-US" -O firefox.tar.bz2 &&\
+    tar xjvf firefox.tar.bz2 && mv /tmp/firefox /opt/firefox-evergreen &&\
     cd /var/www/discourse && sudo -E -u discourse -H yarn install
 
 RUN cd /var/www/discourse && sudo -E -u discourse -H bundle exec rake plugin:install_all_official &&\

GitHub sha: 4f29decec9238444b2c5b3a5b01788fe1a182f78

This commit appears in #570 which was approved by danielwaterworth. It was merged by Falco.