Fix 404 warnings from headless Chrome during tests caused by trying to
load non-existent image URLs in the anchoring regression tests.

The previous method of setting the `__hypothesis_frame` property on the
Window did not work. I haven't investigated in detail why, but the
alternate method of setting this property used here works instead.

Fix adder toolbar tests in browsers (eg. Chrome) which natively support
Shadow DOM v1. The test for Shadow DOM v0 failed because the implementation
feature-detected and used the Shadow DOM v1 method
`Element.prototype.attachShadow` instead.

Fix the issue by patching the test element to hide the native Shadow DOM
methods if they exist.

`uri` is a mandatory property of actual annotations. The absence was
causing some tests to fail in Chrome due to the URL constructor being
called with `undefined`.

`toLocaleTimeString()` in Chrome produces an `hh:mm:ss` output on my
system whereas the rendered timestamp only has `hh:mm`.

Re-using `format` from date-util avoids this hazard.

Add missing arguments to `Element#setAttribute` and
`Selection#collapse`.

PhantomJS allowed these missing arguments but other browsers, eg.
Chrome, do not.

Convert PdfSidebar to JS

Fix "No results for {query}" message

Usage of `vm.search.query` in the `<sidebar-content>` template was
incorrect. `vm.search` is always set and `query` is a function that
returns a string, not a string.

Fixes #9

Handle non percent-encoded URLs when replacing links with media embeds

When a user pastes a link to a video or audio file in an annotation,
handle the case where the link contains non-ASCII characters but the
link's text has not been percent-encoded.

In that case the link's text content will be the unencoded form of the
URL, but the `link.href` property will return the percent-encoded form,
so the two do not compare equal and therefore the link was not replaced.

ES 6 does not provide a direct equivalent for CoffeeScript's static
class properties so the initialization of `options` has been refactored
to use `Object.assign()` as a more idiomatic way to combine the config
args passed to the constructor with the defaults for `PdfSidebar`.

Convert annotator/plugin/document.coffee to JS

anonymize collected IP addresses for GDPR

As a part of https://github.com/hypothesis/product-backlog/issues/653

Enable https://github.com/probot/stale

Shorten very long lines produced by decaffeinate

Clean up output from `decaffeinate`.

 - Remove unnecessary `return` statements
 - Rename `Document` to `DocumentMeta` to avoid conflict with global
   `Document` and match the name used in `document.js`
 - Disable ESLint bind warnings. The use here is appropriate.

Clean up various aspects of `decaffeinate`'s conservative output.

 - Rename `Document` class to `DocumentMeta` to avoid conflict with
   `Document` global
 - Remove class wrapper
 - Remove method `this` binding
 - Remove unnecessary `Array.from` calls
 - Remove unnecessary `return` statements

Initial automated CoffeeScript => JS conversion using:

```
decaffeinate <CoffeeScript file>
eslint --fix <JS file>
```

Fix document metadata tests in chrome

Update Yarn lockfile following addition of cross-env in previous commit.

issue #659 make build platform independent by using cross-env

A `<link>` tag with a relative URL from a previous test was causing
problems in Chrome when testing the behavior of `Document#uri` in
documents with a non-HTTP/file `<base>`.

That is an edge case which we may want to cover at some point, but the
more significant issue is that the `Document#uri` tests were not
isolated from the earlier ones. Modify the `createDoc` helper so that it
uses a blank HTML document instead of using the global `document`
object.

The `Document` class for reading DOM document metadata takes an optional
DOM `Document` constructor argument as a test seam.

However the actual code only used the injected document in some places,
in others it used jQuery which in turn reads from the global
`window.document`.

Refactor this code to use the injected DOM Document everywhere and
remove the jQuery dependency.

Upgrade dependencies to fix compatibility with Node v10

Upgrade dependencies using `yarn upgrade`. This fixes dependency
installation with Node v10.

change links in help panel

"send a suppport ticket" now leads to `https://web.hypothes.is/get-help`
and "visit our help documents" leads to `https://web.hypothes.is/help`