devops: attempt to add mac 10.14 (#2076)

.travis.yml

@@ -1,6 +1,19 @@
 language: node_js
-os: linux
+notifications:
+  email: false
+
+install:
+- npm ci
+
+cache:
+  directories:
+  - node_modules
+
+jobs:
+  include:
+    - os: linux
       dist: bionic
+      node_js: '12'
       addons:
         apt:
           packages:
@@ -24,19 +37,17 @@ addons:
           - libgbm1
           # this is needed for running headful tests
           - xvfb
-notifications:
-  email: false
-install:
-- npm ci
-cache:
-  directories:
-  - node_modules
       script:
         - npm run lint
         - xvfb-run --auto-servernum npm run ctest
         - xvfb-run --auto-servernum npm run ftest
         - xvfb-run --auto-servernum npm run wtest
-jobs:
+    - os: osx
-  include:
+      osx_image: xcode11.3
-  - node_js: '12'
+      node_js: '12'
+      script:
+        - npm run lint
+        - npm run ctest
+        - npm run ftest
+        - npm run wtest