This code comes from an externally managed library, available at
<https://github.com/mozilla/fathom>. Bugs should be reported directly
upstream and integrated back here.

In order to regenerate this file, do the following:

* Run:

  $ git clone git@github.com:mozilla/fathom.git && cd fathom/fathom

* Ensure that [this pull request](https://github.com/mozilla/fathom/pull/311)
  is either landed or been applied to the latest code you want to bundle.
* Then run:

  $ make bundleESModule
  $ export MOZ_FATHOM="../../mozilla-central/toolkit/modules/third_party/fathom"
  $ cat $MOZ_FATHOM/fx-header dist/fathom.js > $MOZ_FATHOM/fathom.mjs