Remove stable builds from the Travis maxtrix
diff --git a/.travis.yml b/.travis.yml
index 32aa295..910f2fa 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -1,18 +1,12 @@
 language: dart
 dart:
   - dev
-  - stable
 
 dart_task:
   - test
   - dartfmt
   - dartanalyzer
 
-matrix:
-  allow_failures:
-    # Some tests are flaky on 1.x
-    - dart: stable
-
 # Only building master means that we don't run two builds for each pull request.
 branches:
   only: [master]