Convert src/annotator/test to ES modules

src/annotator/test/adder-test.js

-const adder = require('../adder');
+import * as adder from '../adder';
 
 function rect(left, top, width, height) {
   return { left: left, top: top, width: width, height: height };

src/annotator/test/annotation-counts-test.js

-const annotationCounts = require('../annotation-counts');
+import annotationCounts from '../annotation-counts';
 
 describe('annotationCounts', function() {
   let countEl1;

src/annotator/test/annotation-sync-test.js

-const EventEmitter = require('tiny-emitter');
+import EventEmitter from 'tiny-emitter';
 
-const AnnotationSync = require('../annotation-sync');
+import AnnotationSync from '../annotation-sync';
 
 describe('AnnotationSync', function() {
   let createAnnotationSync;

src/annotator/test/features-test.js

-const events = require('../../shared/bridge-events');
-const features = require('../features');
-const { $imports } = require('../features');
+import events from '../../shared/bridge-events';
+import features from '../features';
+import { $imports } from '../features';
 
 describe('features - annotation layer', function() {
   let featureFlagsUpdateHandler;

src/annotator/test/range-util-test.js

-const rangeUtil = require('../range-util');
+import * as rangeUtil from '../range-util';
 
 function createRange(node, start, end) {
   const range = node.ownerDocument.createRange();

src/annotator/test/selections-test.js

-const observable = require('../util/observable');
-const selections = require('../selections');
+import selections from '../selections';
+import * as observable from '../util/observable';
 
 function FakeDocument() {
   const listeners = {};

src/annotator/test/sidebar-trigger-test.js

-const sidebarTrigger = require('../sidebar-trigger');
+import sidebarTrigger from '../sidebar-trigger';
 
 describe('sidebarTrigger', function() {
   let triggerEl1;