My personal workflow is to develop against the www-modern release
channel, with the variant flags enabled, because it encompasses the
largest set of features. Then I rely on CI to run the tests against
all the other configurations.
So in practice, I almost always run
```
yarn test -r=www-modern --variant TEST_FILE
```
instead of
```
yarn test TEST_FILE
```
So, I've updated the `yarn test` command to use those options
by default.
dd8552ae0d