Allow dev to fail on travis (flutter#71)

goderbauer · web-flow · commit 3b8d74b7ef40 · 2018-02-12T10:00:40.000-08:00
diff --git a/.travis.yml b/.travis.yml
@@ -4,3 +4,6 @@ dart:
   - stable
   - dev
 script: ./tool/travis.sh
+matrix:
+  allow_failures:
+    - dart: dev
