Run browser tests in chrome (#87)

diff --git a/.travis.yml b/.travis.yml
index 5fee674..6d2f996 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -6,7 +6,7 @@
 
 dart_task:
   - test: -p vm
-  - test: -p firefox -j 1
+  - test: -p chrome
   - dartanalyzer: --fatal-warnings --fatal-infos .
 
 matrix: