Remove checks for IE 11 in `TagEditor` component

`TagEditor` tested if the browser was IE 11 to determine whether to
check the `inputType` property of `InputEvent`. However it is not only
IE 11 that did not support this property.

From reading the comments in https://github.com/hypothesis/client/pull/1558 it
appears that the `inputType` checks was originally added to resolve an
issue with accepting suggestions by pressing Enter in an earlier version
of `TagEditor` that used the `<datalist>` element. As far as I can tell
this is no longer applicable. `<datalist>` was replaced by a custom UI
and accepting suggestions by pressing Enter works without this logic.
Therefore this commit removes it entirely.

src/sidebar/components/tag-editor.js

 import { createElement } from 'preact';
-import { useMemo, useRef, useState } from 'preact/hooks';
+import { useRef, useState } from 'preact/hooks';
 import propTypes from 'prop-types';
 
 import { withServices } from '../util/service-context';
-import { isIE11 } from '../../shared/user-agent';
 
 import AutocompleteList from './autocomplete-list';
 import { normalizeKeyName } from '../../shared/browser-compatibility-utils';
@@ -55,8 +54,6 @@ function TagEditor({
     setSuggestionsListOpen(false);
   });
 
-  const ie11 = useMemo(() => isIE11(), []);
-
   /**
    * Retrieve the current trimmed text value of the tag <input>
    */
@@ -120,20 +117,9 @@ function TagEditor({
     }
   };
 
-  /**
-   *  Update the suggestions if the user changes the value of the input
-   *
-   * @param {import("preact").JSX.TargetedEvent<HTMLInputElement, InputEvent>} e
-   */
-  const handleOnInput = e => {
+  const handleOnInput = () => {
     onTagInput?.(pendingTag());
-    if (
-      e.inputType === 'insertText' ||
-      e.inputType === 'deleteContentBackward' ||
-      ie11 // inputType is not defined in IE 11, so trigger on any input in this case.
-    ) {
     updateSuggestions();
-    }
   };
 
   /**

src/sidebar/components/test/tag-editor-test.js

@@ -17,7 +17,6 @@ describe('TagEditor', function () {
   let fakeOnAddTag;
   let fakeOnRemoveTag;
   let fakeOnTagInput;
-  let fakeIsIE11;
 
   function createComponent(props) {
     // Use an array of containers so we can test more
@@ -46,16 +45,10 @@ describe('TagEditor', function () {
     fakeOnRemoveTag = sinon.stub();
     fakeOnTagInput = sinon.stub();
     fakeServiceUrl = sinon.stub().returns('http://serviceurl.com');
-    fakeIsIE11 = sinon.stub().returns(false);
     fakeTagsService = {
       filter: sinon.stub().returns(['tag4', 'tag3']),
     };
     $imports.$mock(mockImportedComponents());
-    $imports.$mock({
-      '../../shared/user-agent': {
-        isIE11: fakeIsIE11,
-      },
-    });
   });
 
   afterEach(function () {
@@ -91,12 +84,7 @@ describe('TagEditor', function () {
   }
   // Simulates typing text
   function typeInput(wrapper) {
-    if (!fakeIsIE11()) {
     wrapper.find('input').simulate('input', { inputType: 'insertText' });
-    } else {
-      // IE11 does not have an inputType key.
-      wrapper.find('input').simulate('input', {});
-    }
   }
 
   it('adds appropriate tag values to the elements', () => {
@@ -417,9 +405,7 @@ describe('TagEditor', function () {
     });
 
     describe('navigating suggestions via keyboard', () => {
-      [true, false].forEach(ie11 => {
       it('should set the initial `activeItem` value to -1 when opening suggestions', () => {
-          fakeIsIE11.returns(ie11);
         const wrapper = createComponent();
         wrapper.find('input').instance().value = 'non-empty';
         typeInput(wrapper);
@@ -428,7 +414,6 @@ describe('TagEditor', function () {
       });
 
       it('should increment the `activeItem` when pressing down circularly', () => {
-          fakeIsIE11.returns(ie11);
         const wrapper = createComponent();
         wrapper.find('input').instance().value = 'non-empty';
         typeInput(wrapper);
@@ -443,7 +428,6 @@ describe('TagEditor', function () {
       });
 
       it('should decrement the `activeItem` when pressing up circularly', () => {
-          fakeIsIE11.returns(ie11);
         const wrapper = createComponent();
         wrapper.find('input').instance().value = 'non-empty';
         typeInput(wrapper);
@@ -457,7 +441,6 @@ describe('TagEditor', function () {
       });
 
       it('should set `activeItem` to -1 when clearing the suggestions', () => {
-          fakeIsIE11.returns(ie11);
         const wrapper = createComponent();
         wrapper.find('input').instance().value = 'non-empty';
         typeInput(wrapper);
@@ -471,7 +454,6 @@ describe('TagEditor', function () {
       });
     });
   });
-  });
 
   describe('accessibility attributes and ids', () => {
     it('creates multiple <TagEditor> components with unique autocomplete-list `id` props', () => {