These were not converted in the previous commit as they were not
top-level statements in the file.

Convert text highlighter to JS

Convert src/boot to ES modules

 - Add missing parameter / return type docs
 - Update a Chrome bug tracker issue link

Remove the highlighter implementation abstraction layer in
src/annotator/highlighter since only one type of highlighter was ever
implemented and convert the one implementation in
src/annotator/highlighter/dom-wrap-highlighter/index.coffee to JS as
src/annotator/highlighter.js.

Convert remaining sidebar files to ES modules

Use the convert-to-es-modules script to convert the remaining
CommonJS/Node module files in src/sidebar/ to ES modules.

Convert src/sidebar/directives to ES modules

This directory is likely to go away soon as part of the Angular =>
Preact migration.

Nevertheless, I used the convert-to-es-modules script on it to convert
to ES modules so we can complete that migration first.

This is mostly to make it easier for the convert-to-es-modules script to
preserve comments when these modules are converted to ES modules.
However it may also be useful for debugging.

Convert src/sidebar/store to ES modules

This import should be hoisted to the top level of the module but a naive change to do this did not work. I suspect this relates to the circular nature of the
import, but it needs investigating. This change enables the code to
continue working until then.

`$imports` is now a separate named export rather than a property of the
default export.

After converting the module under test to an ES module the mocked functions are now properties of the default export rather than named exports.

Use the convert-to-es-modules script from the frontend-toolkit repo to
convert src/sidebar/store to ES modules.

Convert src/sidebar/services to ES modules

This comment was copied from the line where the `CACHE_TTL` var was
defined when converting to ES modules.

This imports from `src/sidebar/services` so it needed to be converted at
the same time as the modules in that directory.

Move an `events` export from being a property of the default export to a
separate named export, which is more appropriate for ES modules.

Use the convert-to-es-modules script from the frontend-toolkit repo to
convert services to ES modules.

Move new-annotation initialization into the store

Bump core-js from 3.4.8 to 3.6.3

Bump @sentry/browser from 5.10.2 to 5.11.0

Move initialization for new (unsaved) annotations from the (legacy)
annotation component’s controller into the `annotations` store module.

Bump preact from 10.1.1 to 10.2.1

Bump sass from 1.24.2 to 1.24.4

Convert src/sidebar/components to ES modules

This mocking broke after the ES module conversion. Since the mocked
module just exports a set of constants, we can just avoid mocking it.

Export `updateModel` as a separate export rather than a property of the
default export, since this is how the test expects to import it.

Use the convert-to-es-modules package from the frontend-toolkit repo to
convert CommonJS/Node require syntax to ES modules.

As well as the module syntax conversion, this script also has the effect
of normalizing the sorting and grouping of imports according to the
following convention:

 - Imports are grouped into 3 categories: Vendor, same package but other
   directory (as calling module), same directory as calling module
 - Imports are sorted by module path

Import specifiers are untouched.

Convert sidebar entry point to ES modules

Bump sinon from 8.0.2 to 8.0.4

Bumps [core-js](https://github.com/zloirock/core-js) from 3.4.8 to 3.6.3.
- [Release notes](https://github.com/zloirock/core-js/releases)
- [Changelog](https://github.com/zloirock/core-js/blob/master/CHANGELOG.md)
- [Commits](https://github.com/zloirock/core-js/compare/v3.4.8...v3.6.3)
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