Travis: fix build

Author: olleolleolle

.travis.yml

@@ -1,15 +1,20 @@
-sudo: false
-
 addons:
-  firefox: "latest"
+  firefox: 54.0
+
+services:
+  - xvfb
+
 before_install:
-  - "export DISPLAY=:99.0"
-  - "sh -e /etc/init.d/xvfb start"
-  - wget https://github.com/mozilla/geckodriver/releases/download/v0.16.1/geckodriver-v0.16.1-linux64.tar.gz
+  - wget https://github.com/mozilla/geckodriver/releases/download/v0.18.0/geckodriver-v0.18.0-linux64.tar.gz
   - mkdir geckodriver
-  - tar -xzf geckodriver-v0.16.1-linux64.tar.gz -C geckodriver
+  - tar -xzf geckodriver-v0.18.0-linux64.tar.gz -C geckodriver
   - export PATH=$PATH:$PWD/geckodriver
-  - gem install bundler
+  - gem install bundler -v'< 2'
+
+before_script:
+  - "export DISPLAY=:99.0"
+  - "sh -e /etc/init.d/xvfb start"
+  - sleep 3 # give xvfb some time to start
 
 language: ruby
 
@@ -46,4 +51,3 @@ matrix:
     - rvm: ruby-head
     - rvm: jruby-head
     - rvm: rbx-2
-