Update lib/browserDocument.js

Co-authored-by: hasezoey <hasezoey@gmail.com>

Author: vkarpov15

lib/browserDocument.js

@@ -97,7 +97,7 @@ Document.$emitter = new EventEmitter();
  * ignore
  */
 
-Document.prototype._execDocumentPreHooks = function _execDocumentPreHooks(opName) {
+Document.prototype._execDocumentPreHooks = async function _execDocumentPreHooks(opName) {
   return this._middleware.execPre(opName, this, []);
 };