feat(ci): Name the xbrowser unit job (#148)

- Add a `name` to the xbrowser unit test job ([docs](https://docs.travis-ci.com/user/customizing-the-build#Naming-Jobs-within-Matrices))

Found this the other day, I think it's a new feature... [before](https://travis-ci.org/optimizely/javascript-sdk/builds/399797127), [after](https://travis-ci.org/optimizely/javascript-sdk/builds/407273017)

Author: spencerwilson-optimizely

.travis.yml

@@ -16,7 +16,8 @@ env:
   - secure: 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
 matrix:
   include:
-  - node_js: '10'
+  - name: Cross-browser unit tests
+    node_js: '10'
     script: npm run test-xbrowser
 before_install: cd packages/optimizely-sdk
 install: npm install