Customize build steps based on Dart version.

Author: evanweible-wf

.travis.yml

@@ -1,17 +1,26 @@
 language: dart
 
-dart:
-  - 2.3.0
-  - stable
-  - dev
+jobs:
+  include:
+    - dart: "2.4.1"
+      name: "SDK: 2.4.1"
+      script:
+        - pub run dart_dev analyze
+        - pub run dart_dev test
+    - dart: stable
+      name: "SDK: stable"
+      script:
+        - pub run dart_dev analyze
+        - pub run dependency_validator -i pedantic
+        - pub run dart_dev format --check
+        - pub run dart_dev test
+        - pub publish --dry-run
+    - dart: dev
+      name: "SDK: dev"
+      script:
+        - pub run dart_dev analyze
+        - pub run dart_dev test
 
-sudo: required
-addons:
-  chrome: stable
-
-script:
-  - pub run dependency_validator -i pedantic
-  - pub run dart_dev analyze
-  - pub run dart_dev format --check
-  - pub run dart_dev test
-  - pub publish --dry-run
+cache:
+  directories:
+    - "$HOME/.pub-cache"