Use compat build of Fluent

[kellda]

Use compat build of fluent to support Edge older than 79.

See projectfluent/fluent.js#431 and WebThingsIO/gateway#2238

Fixes #1487

[stasm]

Hi, I'm the maintainer of Fluent and the @fluent family of packages on npm. While using the compat build will likely help fix the issue at hand, I'd like to point out that last week I released new versions of all @fluent packages which don't ship with the compat.js builds anymore. This includes @fluent/bundle 0.16.0. The code that we now ship is transpiled by TypeScript to ES2018. More info: projectfluent/fluent.js#472, projectfluent/fluent.js#479, as well as projectfluent/fluent.js#431 (comment).

If you go ahead and merge this, please do it as a hot-fix rather than a longer-term solution. In my opinion the right solution is to transpile node_modules/@fluent during Send's build. This will help ensure that you ship code which meets your compatibility criteria to the letter, and will make it easier to upgrade to new versions of @fluent/bundle in the future.

Interestingly, it looks like Send's config for Webpack already explicitly includes node_modules/@fluent:

send/webpack.config.js

Line 106 in a429b89

path.resolve(__dirname, 'node_modules/@fluent'),

Perhaps that config line doesn't work as intended and that's what's causing the bug?

[dannycoates]

Thanks for looking at this @kellda. I fixed it a different way by adding edge 18 to the browserlist file