[core] fixing karma timeout error in travis (vmware-archive#666)

Fixes vmware-archive#666.

Signed-off-by: Jeeyun Lim <jeeyun.lim@gmail.com>

.travis.yml

@@ -32,9 +32,15 @@ cache:
     - node_modules
 
 before_install:
-  - export CHROME_BIN=chromium-browser
+  - export CHROME_BIN=/usr/bin/google-chrome
   - export DISPLAY=:99.0
-  - sh -e /etc/init.d/xvfb start
+
+before_script:
+  - npm install -g gemini
+  - npm install -g selenium-standalone
+  - selenium-standalone install
+  - xvfb-run --server-args="-screen 0, 1600x2400x24" selenium-standalone start > selenium.txt &
+  - sleep 5
 
 script:
   - gulp $TEST_SUITE # run unit test, css regression, and css reference in parallel