Switch to Chrome (over FF) in CI (#85)

diff --git a/.travis.yml b/.travis.yml
index a25a59e..e982192 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -7,7 +7,7 @@
 dart_task:
   - test: -p vm
     xvfb: false
-  - test: -p firefox
+  - test: -p chrome
   - dartanalyzer: --fatal-warnings --fatal-infos .
 
 matrix: