Stop testing on SDK 2.8.4

pkgs/watcher/.travis.yml

diff --git a/pkgs/watcher/.travis.yml b/pkgs/watcher/.travis.yml
index 2c6dc5a..ca68b17 100644
--- a/pkgs/watcher/.travis.yml
+++ b/pkgs/watcher/.travis.yml
@@ -2,7 +2,6 @@
 
 dart:
 - dev
-- 2.8.4
 
 os:
 - linux
@@ -16,9 +15,6 @@
   include:
   - dart: dev
     dart_task: dartfmt
-  - dart: 2.8.4
-    dart_task:
-      dartanalyzer: --fatal-warnings .
   - dart: dev
     dart_task:
       dartanalyzer: --fatal-warnings --fatal-infos .