- Tighten panel subheader and sub-panel navigation links
- Make vertical and horizontal rhythm consistent

By changing the temporary element for holding text from a `span` to a
`pre`, line breaks in formatted strings may be retained when copying
to the clipboard

NB: This change cannot be directly tested

Separate `asEncodedURLString` into two constituent methods, allowing
access to an un-encoded `asFormattedString`, which returns a string
formatted for (e.g.) copying to the clipboard.

Replace Help and Tutorial panels with single, preact panel

Improve tab bar accessibility

Help & Tutorial 4/n: Add support for status-change callback to `SidebarPanel`

Help & Tutorial 3/n: Refactor how auto-display of tutorial is determined

Setting an `ariaSelected` prop works in the latest Safari because elements have
an `ariaSelected` property as part of the Accessibility Object Model
implementation [1]. This is not yet implemented in Chrome however, so
the `ariaSelected` prop gets mapped to an `ariaselected` attribute. We
need to set the `aria-selected` attribute however.

[1] https://github.com/WICG/aom/blob/gh-pages/explainer.md#reflecting-aria-attributes

Update mobile testing docs

Add screenshot to clarify what change the developer might need to make.

Make boot URL templating work in IE 11 / early Edge

Convert excerpt (1/n) - Fix several issues with Angular <-> Preact wrapper

Update the documentation for testing the client on mobile devices
following the merge of https://github.com/hypothesis/h/pull/5758.

 - Remove the step involving changing the `CLIENT_URL` env var in the h
   dev environment

 - Add a Troubleshooting section

Change approach to mocking components in unit tests

Shallow rendering with Enzyme's `shallow` function conflates two changes in
rendering behavior:

 1. Only rendering "one level deep" so that a test for a component is
    isolated from the details of any child components

 2. In React (but not Preact) rendering to a data structure instead of
    real DOM nodes. Even though Preact still renders real DOM nodes,
    Enzyme's shallow rendering API removes many of the features of
    `mount` rendering

In practice, we only used shallow rendering for (1) and we have found
that there are use cases where we want (1) but still want to be able to
interact with the real DOM nodes (ie. we don't want (2)). The need to
use different mocking approaches and understand the conflated behaviors
mentioned above has been a source of confusion for developers.

This commit changes the mocking approach to always use a pattern that we
have until now only used selectively. Enzyme's `mount` rendering mode is
always used, but a utility function, `mockImportedComponents`, is used
with our existing import mocking (via babel-plugin-mockable-imports) to
semi-automatically mock all imported components.

Each test has been changed as follows:

 1. Replace `shallow` with `mount`

 2. Call `ComponentUnderTest.$imports.$mock(mockImportedComponents())`
    in the test setup to mock all imported components, but not helper
    components defined in the same file.

 3. Call `ComponentUnderTest.$imports.$restore()` in test cleanup, if
    the test was not already doing that.

 4. Replace uses of (`wrapper.find(SomeChildComponent)`) with
    (`wrapper.find('SomeChildComponent')`. This is necessary because the
    mocked component no longer has the same identity as the original, so
    we look it up by name instead.

This will be used as an alternative to shallow rendering to facilitate
unit-testing of Preact components.

 - Add ARIA roles to the tab bar and individual tabs
 - Make the tab items tab-focusable
 - Indicate the selected tab using `aria-selected`

This fixes an issue with `useLayoutEffect` where it could run before a
component's DOM node became connected to the document, preventing the
effect from measuring the node.

It turns out that `$onChanges` is invoked both when the component is
initially created as well as subsequent updates. Therefore `$onInit` and
`$onChanges` duplicated work and components were rendered twice during
initial creation.

Allow function props passed to Preact components wrapped with
`wrapReactComponent` to be invoked when a digest cycle is already active
for some reason. In that case using `$scope.$apply` triggers an error.

This scenario is rare, as callbacks are usually invoked in response to
events that happen outside of Angular, but changes made by Angular code
can indirectly cause Preact components to invoke callbacks. For example,
in layout effects which run at the end of a `render` call.

Make the boot URL templating used during development work in IE 11 and
Edge. In IE 11 `document.currentScript` is not available and in IE 11 /
early Edge, the `URL` constructor is not available before polyfills have
been loaded.

The `document.currentScript` fallback here assumes that the boot script
has been loaded synchronously so that the boot script is the last
`<script>` element on the page at the point when it runs.

Also add a fast path for production builds where URLs do not contain
template params.

This is a follow up to #1441

Fix PDF anchoring when annotation refers to last text on a page

Bump eslint from 6.5.1 to 6.6.0

Bump sass from 1.23.0 to 1.23.1

Whether to add commas after the final argument in array and object
literals or function argument lists is handled by Prettier.

Bump scroll-into-view from 1.11.0 to 1.12.2

Bump autoprefixer from 9.6.5 to 9.7.0

Merge pull request #1460 from hypothesis/dependabot/npm_and_yarn/babel-plugin-transform-async-to-promises-0.8.15

Bump babel-plugin-transform-async-to-promises from 0.8.14 to 0.8.15

Bump puppeteer from 1.20.0 to 2.0.0

Bumps [autoprefixer](https://github.com/postcss/autoprefixer) from 9.6.5 to 9.7.0.
- [Release notes](https://github.com/postcss/autoprefixer/releases)
- [Changelog](https://github.com/postcss/autoprefixer/blob/master/CHANGELOG.md)
- [Commits](https://github.com/postcss/autoprefixer/compare/9.6.5...9.7.0)
Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

Bumps [eslint](https://github.com/eslint/eslint) from 6.5.1 to 6.6.0.
- [Release notes](https://github.com/eslint/eslint/releases)
- [Changelog](https://github.com/eslint/eslint/blob/master/CHANGELOG.md)
- [Commits](https://github.com/eslint/eslint/compare/v6.5.1...v6.6.0)
Signed-off-by: dependabot-preview[bot] <support@dependabot.com>