Travis: basic (non-test) sanity checks

Author: kevmoo

.travis.yml

@@ -0,0 +1,16 @@
+language: dart
+sudo: false
+dart:
+  - dev
+  - stable
+  - 1.23.0
+dart_task:
+  - dartanalyzer: --fatal-warnings .
+  # Sadly, this is a no-op now.
+  # https://github.com/travis-ci/travis-ci/issues/7632
+  # https://github.com/travis-ci/travis-ci/issues/7639
+  # Leaving it here so it'll kick in when the above is fixed
+  - dartfmt
+cache:
+  directories:
+    - $HOME/.pub-cache