v1.584.0

Rewrite selection buffering implementation

Rewrite the selection change observer in `src/annotator/selections` to
make it easier to understand how this functionality works and change it
in future.

The major change is to remove the dependency on the `Observable` class
provided by `zen-observable`, which adds cognitive overhead here, isn't used
elsewhere and is stuck on an old version due to subtle breaking changes in newer releases.

Replace it instead with a `SelectionObserver` class which is modeled
after DOM APIs like `MutationObserver`. It takes a callback in the
constructor that is invoked with the selected `Range` or `null` when the
selection changes and provides a `disconnect` method which stops
watching for future changes. The implementation only uses DOM APIs.

v1.583.0

• Remove ES 2015 and ES 2016 polyfill sets
  #2702

v1.582.0

• Replace babel-plugin-angularjs-annotate with babel-plugin-inject-args
  #2700

v1.581.0

• Don't show edited timestamps if annotations haven't been updated
  #2690

v1.580.0

Bump @sentry/browser from 5.27.1 to 5.27.2

Bumps [@sentry/browser](https://github.com/getsentry/sentry-javascript) from 5.27.1 to 5.27.2.
- [Release notes](https://github.com/getsentry/sentry-javascript/releases)
- [Changelog](https://github.com/getsentry/sentry-javascript/blob/master/CHANGELOG.md)
- [Commits](https://github.com/getsentry/sentry-javascript/compare/5.27.1...5.27.2)

Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

v1.579.0

• Fix browser support check failure if boot script loaded before body
  #2691

v1.578.0

• Refactor buckets to add a11y, convert to preact
  #2688

v1.577.0

• Consolidate clean-theme class naming and organization
  #2671

v1.576.0

• Fail more gracefully in unsupported versions of Edge Legacy
  #2685

v1.575.0

Bump commander from 6.1.0 to 6.2.0

Bumps [commander](https://github.com/tj/commander.js) from 6.1.0 to 6.2.0.
- [Release notes](https://github.com/tj/commander.js/releases)
- [Changelog](https://github.com/tj/commander.js/blob/master/CHANGELOG.md)
- [Commits](https://github.com/tj/commander.js/compare/v6.1.0...v6.2.0)

Signed-off-by: dependabot-preview[bot] <support@dependabot.com>