Travis: fix xvfb config (#203)

diff --git a/.travis.yml b/.travis.yml
index a21349b..12aac88 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -44,9 +44,3 @@
   directories:
     - $HOME/.pub-cache
     - .dart_tool
-
-# Necessary for Chrome and Firefox to run
-before_install:
- - export DISPLAY=:99.0
- - sh -e /etc/init.d/xvfb start
- - "t=0; until (xdpyinfo -display :99 &> /dev/null || test $t -gt 10); do sleep 1; let t=$t+1; done"
diff --git a/tool/travis.sh b/tool/travis.sh
index 748d619..36e5216 100755
--- a/tool/travis.sh
+++ b/tool/travis.sh
@@ -47,12 +47,12 @@
   dartdevc_test) echo
     echo -e '\033[1mTASK: dartdevc_test\033[22m'
     echo -e 'pub run build_runner test -- -p chrome'
-    pub run build_runner test -- -p chrome || EXIT_CODE=$?
+    xvfb-run pub run build_runner test -- -p chrome || EXIT_CODE=$?
     ;;
   dart2js_test) echo
     echo -e '\033[1mTASK: dart2js_test\033[22m'
     echo -e 'pub run test -p chrome'
-    pub run test -p chrome || EXIT_CODE=$?
+    xvfb-run pub run test -p chrome || EXIT_CODE=$?
     ;;
   coverage) echo
     echo -e '\033[1mTASK: coverage\033[22m'