Stop testing Dartium

.travis.yml

diff --git a/.travis.yml b/.travis.yml
index f94c273..da93bb8 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -1,5 +1,5 @@
 language: dart
-sudo: false
+
 dart:
   - dev
   - stable
@@ -7,14 +7,12 @@
 dart_task:
   - test: --platform vm
   - test: --platform firefox
-  - test: --platform dartium
-    install_dartium: true
 
 matrix:
   include:
-    - dart: stable
+    - dart: dev
       dart_task: dartfmt
-    - dart: stable
+    - dart: dev
       dart_task: dartanalyzer
 
 # Only building master means that we don't run two builds for each pull request.