insertElement fails with a few cells selected

[Sa'ar Zac Elias]

Similar to #6432 and #6986. Behaviour of insertElement should be revised to handle a few cells selected.

[Jakub Ś]

1. Create default table,
   2. Select few cells e.g. two in one row or two in one column
   3. Click create table button
   4. Press OK.

Result: JS error occurs
Message: this.$ is undefined
Code: this.$.appendChild( node.$ );
Line :201
URI: /3.6.1/ckeditor/_source/core/dom/element.js

Issue is only reproducible in Firefox as it is the only browser which allows for such selection.

[Jakub Ś]

I'm closing this issue as in v4 it has changed into more serious one #10652.