Update Travis-CI to test on dev branch (dart-lang/term_glyph#15)

pkgs/term_glyph/.travis.yml

diff --git a/pkgs/term_glyph/.travis.yml b/pkgs/term_glyph/.travis.yml
index 2d56165..0b96899 100644
--- a/pkgs/term_glyph/.travis.yml
+++ b/pkgs/term_glyph/.travis.yml
@@ -1,25 +1,22 @@
 language: dart
 
 dart:
-- preview/raw/2.10.0-0.2-dev
+- dev
 
 jobs:
   include:
     - stage: analyze_and_format
-      name: "Analyze test/"
-      dart: preview/raw/2.10.0-0.2-dev
+      name: "Analyze"
       os: linux
-      script: dartanalyzer --enable-experiment=non-nullable --fatal-warnings --fatal-infos .
+      script: dartanalyzer --fatal-warnings --fatal-infos .
     - stage: analyze_and_format
       name: "Format"
-      dart: preview/raw/2.10.0-0.2-dev
       os: linux
       script: dartfmt -n --set-exit-if-changed .
     - stage: test
       name: "Vm Tests"
-      dart: preview/raw/2.10.0-0.2-dev
       os: linux
-      script: pub run --enable-experiment=non-nullable test -p vm 
+      script: pub run test -p vm 
 
 stages:
   - analyze_and_format