Fix Travis production builds (#2933)

* Fix Travis production builds

* Fix Travis production builds, attempt 2

* Remove `allow_failures` in .travis.yml

The reason we allowed the production builds to fail in the first place:

    ❯ git show 532ac0d3f
    commit 532ac0d3f8
    Author: Joseph Frazier <1212jtraceur@gmail.com>
    Date:   2017-06-17 19:37:51 -0400

        Build/test dist/ on Travis (#2176)

        This helps us keep track of whether or not the dist/ build actually
        works (see https://github.com/prettier/prettier/pull/2174). Note that
        the dist/ jobs are allowed to fail, and do not affect overall build
        time, so they shouldn't slow anything down (see
        https://blog.travis-ci.com/2013-11-27-fast-finishing-builds/).

However, as we discovered in #2933 requiring the production builds to
succeed only adds about 1 minute of build time, so it is not worth the
risk of missing that the production builds fail.

.travis.yml

@@ -12,11 +12,9 @@ env:
   - NODE_ENV=development
   - NODE_ENV=production
 matrix:
-  allow_failures:
-    - env: NODE_ENV=production
   fast_finish: true
 install:
-  - yarn --production=false
+  - NODE_ENV=development yarn install
 before_script:
   - if [ "${NODE_ENV}" = "production" ]; then yarn build; fi
 script: