Remove various workarounds for IE 11

Remove workarounds for IE that are no longer needed since IE 11 is not
supported any more.

 - Remove optional and deprecated arguments to `document.createNodeIterator`

 - Update references to IE 11 for checks/code which is still applicable
   to other browsers

 - Remove `window.msCrypto` fallback for `window.crypto`

 - Remove unused `isIE11` helper

 - Remove IE 11 reference in `polyfills/index.js`. We don't actually
   need the check because the browser check in `boot/index.js` will fail
   if `Promise` is missing, but I left it in because that knowledge is
   contained in a separate part of the code and
   `shared/polyfills/index.js` is currently written as if it may be used
   in a pre-ES2015 environment.

src/annotator/anchoring/text-position.js

@@ -26,11 +26,7 @@ export function toRange(root, start, end) {
   // although optional according to the spec.
   const nodeIter = root.ownerDocument.createNodeIterator(
     root,
-    NodeFilter.SHOW_TEXT,
-    null, // filter
-
-    // @ts-ignore - Ignored parameter required for IE 11
-    false // expandEntityReferences
+    NodeFilter.SHOW_TEXT
   );
 
   let startContainer;

src/annotator/highlighter.js

@@ -102,7 +102,7 @@ function drawHighlightsAbovePdfCanvas(highlightEl) {
       // @ts-ignore - `mixBlendMode` property is missing from type definitions.
       svgStyle.mixBlendMode = 'multiply';
     } else {
-      // For older browsers (IE 11, Edge < 79) we draw all the highlights as
+      // For older browsers (eg. Edge < 79) we draw all the highlights as
       // opaque and then make the entire highlight layer transparent. This means
       // that there is no visual indication of whether text has one or multiple
       // highlights, but it preserves readability.
@@ -232,7 +232,7 @@ export function highlightRange(normedRange, cssClass = 'hypothesis-highlight') {
 /**
  * Replace a child `node` with `replacements`.
  *
- * nb. This is like `ChildNode.replaceWith` but it works in IE 11.
+ * nb. This is like `ChildNode.replaceWith` but it works in older browsers.
  *
  * @param {ChildNode} node
  * @param {Node[]} replacements

src/annotator/range-util.js

@@ -51,11 +51,7 @@ function forEachNodeInRange(range, callback) {
   // mandatory in IE although optional according to the spec.
   const nodeIter = /** @type {Document} */ (root.ownerDocument).createNodeIterator(
     root,
-    NodeFilter.SHOW_ALL,
-    null /* filter */,
-
-    // @ts-ignore - Deprecated last parameter. Required for IE 11.
-    false /* expandEntityReferences */
+    NodeFilter.SHOW_ALL
   );
 
   let currentNode;

src/shared/browser-compatibility-utils.js

 /**
  * Normalize a keyboard event key name.
  *
- * Several old browsers, such as IE11, use alternate key
- * names for keyboard events. If any abnormal keys are used,
- * this method returns the normalized name so our UI
- * components don't require a special case.
+ * Some old Microsoft browsers, such as IE 11 and Edge Legacy [1], use non-standard
+ * names for some keys. If any abnormal keys are used, this method returns the
+ * normalized name so our UI components don't require a special case.
+ *
+ * [1] https://caniuse.com/keyboardevent-key
  *
  * @param {string} key - The keyboard event `key` name
  * @return {string} - Normalized `key` name

src/shared/polyfills/index.js

@@ -58,11 +58,9 @@ const needsPolyfill = {
   },
 
   es2018: () => {
-    if (!window.Promise) {
-      // IE11 does not have a Promise object.
-      return true;
-    }
-    return !hasMethods(Promise.prototype, 'finally');
+    return (
+      typeof Promise !== 'function' || !hasMethods(Promise.prototype, 'finally')
+    );
   },
 
   // Test for a fully-working URL constructor.

src/shared/test/user-agent-test.js

-import { isIE11, isMacOS } from '../user-agent';
+import { isMacOS } from '../user-agent';
 
 describe('shared/user-agent', () => {
-  describe('isIE11', () => {
-    it('returns true when the user agent is IE 11', () => {
-      assert.isTrue(
-        isIE11('Mozilla/5.0 (Windows NT 10.0; Trident/7.0; rv:11.0) like Gecko')
-      );
-    });
-
-    it('returns false when the user agent is not IE 11', () => {
-      assert.isFalse(
-        isIE11(
-          'Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/81.0.4044.92 Safari/537.36 Edg/80.0.361.109'
-        )
-      );
-    });
-  });
-
   describe('isMacOS', () => {
     it('returns true when the user agent is a Mac', () => {
       assert.isTrue(

src/shared/user-agent.js

@@ -2,15 +2,6 @@
  * Helper methods to identify browser versions and os types
  */
 
-/**
- * Returns true when the browser is IE11.
- *
- * @param _userAgent {string} - Test seam
- */
-export const isIE11 = (_userAgent = window.navigator.userAgent) => {
-  return _userAgent.indexOf('Trident/7.0') >= 0;
-};
-
 /**
  * Returns true when the OS is Mac OS.
  *

src/sidebar/util/random.js

@@ -10,9 +10,7 @@ function byteToHex(val) {
  * @return {string}
  */
 export function generateHexString(len) {
-  // @ts-ignore - TS doesn't know about `msCrypto`.
-  const crypto = window.crypto || window.msCrypto; /* IE 11 */
   const bytes = new Uint8Array(len / 2);
-  crypto.getRandomValues(bytes);
+  window.crypto.getRandomValues(bytes);
   return Array.from(bytes).map(byteToHex).join('');
 }

src/sidebar/util/sentry.js

@@ -18,8 +18,7 @@ const maxEventsToSendPerSession = 5;
  */
 function currentScriptOrigin() {
   try {
-    // nb. IE 11 does not support `document.currentScript` and this property
-    // is only available while a `<script>` tag is initially being executed.
+    // This property is only available while a `<script>` tag is initially being executed.
     const script = /** @type {HTMLScriptElement} */ (document.currentScript);
     const scriptUrl = new URL(script.src);
     return scriptUrl.origin;