npm install breaks tests

[ryanhamley]

mapbox-gl-js version: 0.45.0

Steps to Trigger Behavior

1. npm install
2. yarn test

Expected Behavior

npm install and yarn install will produce the same output so that all tests will pass correctly

Actual Behavior

npm install bypasses the yarn.lock file and installs a newer version of @mapbox/batfish that breaks some tests.

Possible solution

set up npm install to fallback to yarn with the use-yarn node module

[andrewharvey]

With the latest master and batfish version, the tests pass even when using npm install. That said, I think use-yarn is a good idea to prevent this issue popping up in the future.

[asheemmamoowala]

@ryanhamley The contributing docs only every mention using yarn with this project. Is there a use-case or reason fro needing to support npm?

[ryanhamley]

Just that it's very common for people to use npm install then wonder why things aren't working