title: Material-UI drop-down menu causing error in IE11 after updating to angular 8
body: <p>Angular 8 application with material 8 throws following error on IE11 when the material menu is opened:</p>
  
  <pre><code>Unable to get property 'opacity' of undefined or null reference
  </code></pre>
  
  <p>It worked well with angular 7.2.
  Used IE11 Version: 11.1146.16299.0 Update version: 11.0.125</p>
  
  <p>New project dependency versions:</p>
  
  <pre><code>"dependencies": {
  "@angular/animations": "^8.0.0",
  "@angular/cdk": "^8.0.0",
  "@angular/common": "~8.0.0",
  "@angular/compiler": "~8.0.0",
  "@angular/core": "~8.0.0",
  "@angular/forms": "~8.0.0",
  "@angular/material": "^8.0.0",
  "@angular/platform-browser": "~8.0.0",
  "@angular/platform-browser-dynamic": "~8.0.0",
  "@angular/router": "~8.0.0",
  "classlist.js": "^1.1.20150312",
  "core-js": "^3.1.3",
  "rxjs": "~6.5.2",
  "tslib": "^1.9.0",
  "web-animations-js": "github:angular/web-animations-js#release_pr208",
  "zone.js": "~0.9.1"
  </code></pre>
  
  <p>}</p>
  
  <p>Simple Menu</p>
  
  <pre><code>&lt;mat-menu #appMenu="matMenu"&gt;
    &lt;button mat-menu-item&gt;Menu Item 1&lt;/button&gt;
  &lt;/mat-menu&gt;
  
  &lt;button mat-button [matMenuTriggerFor]="appMenu"&gt;
    Menu
  &lt;/button&gt;
  </code></pre>
  
  <p>Already used pollyfills:</p>
  
  <pre><code>import 'classlist.js';  // Run `npm install --save classlist.js`.
  import 'web-animations-js'; // Run `npm install --save web-animations-js`.
  </code></pre>
  
  <p>IE stack trace:
  <a href="https://i.stack.imgur.com/sOjJE.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/sOjJE.png" alt="IE stack trace"></a></p>
  
  <p>I verified the issue with a newly created angular 8 app containing only the menu in the app component.</p>
  
  <p>Does anyone have any suggestion on how to solve this issue? Thanks</p>