Replace this.async() with setTimeout()

Change-Id: Iaf3169e170e49ae77fbe5c60052ae2d6d280be9d

gr-editor/codemirror-element.js

diff --git a/gr-editor/codemirror-element.js b/gr-editor/codemirror-element.js
index 05a879f..8ea2ead 100644
--- a/gr-editor/codemirror-element.js
+++ b/gr-editor/codemirror-element.js
@@ -62,7 +62,7 @@
     this.scopeSubtree(this.$.wrapper, true);
     // eslint-disable-next-line new-cap
     this._nativeMirror = window.CodeMirror(this.$.wrapper, this._params);
-    this.async(() => {
+    setTimeout(() => {
       this._nativeMirror.refresh();
       this._nativeMirror.focus();
       this._nativeMirror.setSize(null, window.screen.height);