fix(etherpad) fix CORS issues

Avoid modifying the iframe. We don't really need to bubble up mouse
events anymore since the Etherpad frame won't overlap with the toolbar
or filmstrip, so when the user moves over those areas it will just show
up.

modules/UI/etherpad/Etherpad.js

@@ -8,39 +8,6 @@ import Filmstrip from '../videolayout/Filmstrip';
 import LargeContainer from '../videolayout/LargeContainer';
 import VideoLayout from '../videolayout/VideoLayout';
 
-/**
- *
- */
-function bubbleIframeMouseMove(iframe) {
-    const existingOnMouseMove = iframe.contentWindow.onmousemove;
-
-    iframe.contentWindow.onmousemove = function(e) {
-        if (existingOnMouseMove) {
-            existingOnMouseMove(e);
-        }
-        const evt = document.createEvent('MouseEvents');
-        const boundingClientRect = iframe.getBoundingClientRect();
-
-        evt.initMouseEvent(
-            'mousemove',
-            true, // bubbles
-            false, // not cancelable
-            window,
-            e.detail,
-            e.screenX,
-            e.screenY,
-            e.clientX + boundingClientRect.left,
-            e.clientY + boundingClientRect.top,
-            e.ctrlKey,
-            e.altKey,
-            e.shiftKey,
-            e.metaKey,
-            e.button,
-            null // no related element
-        );
-        iframe.dispatchEvent(evt);
-    };
-}
 
 /**
  * Default Etherpad frame width.
@@ -76,26 +43,6 @@ class Etherpad extends LargeContainer {
 
         this.container.appendChild(iframe);
 
-        iframe.onload = function() {
-            // eslint-disable-next-line no-self-assign
-            document.domain = document.domain;
-            bubbleIframeMouseMove(iframe);
-
-            setTimeout(() => {
-                const doc = iframe.contentDocument;
-
-                // the iframes inside of the etherpad are
-                // not yet loaded when the etherpad iframe is loaded
-                const outer = doc.getElementsByName('ace_outer')[0];
-
-                bubbleIframeMouseMove(outer);
-
-                const inner = doc.getElementsByName('ace_inner')[0];
-
-                bubbleIframeMouseMove(inner);
-            }, 2000);
-        };
-
         this.iframe = iframe;
     }