Attempt to address CI failure

```
IE 11.0 (Windows 8.1) ERROR
133
  Expected identifier, string or number
134
  at @stimulus/core/dist/tests/index.js:2281:1
135

136
  SyntaxError: Expected identifier, string or number
137
     at ./packages/@stimulus/polyfills/index.js (@stimulus/core/dist/tests/index.js:2281:1)
```

```
IE 11.0 (Windows 8.1)  target disconnected callback when element is removed FAILED
125
	Promise rejected during "target disconnected callback when element is removed": Object doesn't support property or method 'remove'
126
	TypeError: Object doesn't support property or method 'remove'
127
	   at Anonymous function (eval code:191:25)
```

packages/@stimulus/core/src/tests/modules/target_tests.ts

@@ -127,7 +127,7 @@ export default class TargetTests extends ControllerTestCase(TargetController) {
     this.assert.equal(this.controller.inputTargetDisconnectedCallCountValue, 0)
     this.assert.notOk(disconnectedInput.classList.contains("disconnected"), `expected "${disconnectedInput.className}" not to contain "disconnected"`)
 
-    disconnectedInput.remove()
+    disconnectedInput.parentElement?.removeChild(disconnectedInput)
     await this.nextFrame
 
     this.assert.equal(this.controller.inputTargetDisconnectedCallCountValue, 1)

packages/@stimulus/polyfills/index.js

@@ -19,7 +19,7 @@ if (typeof SVGElement.prototype.contains != "function") {
 // From https://developer.mozilla.org/en-US/docs/Web/API/Node/isConnected#polyfill
 if (!("isConnected" in Node.prototype)) {
   Object.defineProperty(Node.prototype, "isConnected", {
-    get() {
+    get: function() {
       return (
         !this.ownerDocument ||
         !(