Drop Legacy Edge support.

This allows us to move forward without being held back. Microsoft already replaces the Legacy Edge with the new one on supported Windows versions.

js/src/dom/event-handler.js

@@ -6,7 +6,6 @@
  */
 
 import { getjQuery } from '../util/index'
-import { defaultPreventedPreservedOnDispatch } from './polyfill'
 
 /**
  * ------------------------------------------------------------------------
@@ -314,12 +313,6 @@ const EventHandler = {
 
     if (defaultPrevented) {
       evt.preventDefault()
-
-      if (!defaultPreventedPreservedOnDispatch) {
-        Object.defineProperty(evt, 'defaultPrevented', {
-          get: () => true
-        })
-      }
     }
 
     if (nativeDispatch) {

js/src/dom/polyfill.js

@@ -10,20 +10,6 @@ import { getUID } from '../util/index'
 let find = Element.prototype.querySelectorAll
 let findOne = Element.prototype.querySelector
 
-// MSEdge resets defaultPrevented flag upon dispatchEvent call if at least one listener is attached
-const defaultPreventedPreservedOnDispatch = (() => {
-  const e = new CustomEvent('Bootstrap', {
-    cancelable: true
-  })
-
-  const element = document.createElement('div')
-  element.addEventListener('Bootstrap', () => null)
-
-  e.preventDefault()
-  element.dispatchEvent(e)
-  return e.defaultPrevented
-})()
-
 const scopeSelectorRegex = /:scope\b/
 const supportsScopeQuery = (() => {
   const element = document.createElement('div')
@@ -75,6 +61,5 @@ if (!supportsScopeQuery) {
 
 export {
   find,
-  findOne,
-  defaultPreventedPreservedOnDispatch
+  findOne
 }

js/tests/browsers.js

@@ -23,13 +23,6 @@ const browsers = {
     browser: 'Firefox',
     browser_version: 'latest'
   },
-  edgeWin10: {
-    base: 'BrowserStack',
-    os: 'Windows',
-    os_version: '10',
-    browser: 'Edge',
-    browser_version: '16'
-  },
   chromeWin10: {
     base: 'BrowserStack',
     os: 'Windows',