[Edge] Cannot focus widget programmatically at the first try.

[kkrzton]

The parent task is #14819.

Steps to reproduce

1. Go to ​http://ckeditor.com/demo#widgets.
2. Run var editor = CKEDITOR.instances.editor2;editor.widgets.getByElement( editor.editable().findOne( 'pre' ) ).focus(); from the console without focusing the editor.

Expected result

The first code snippet widget in the second editor should be focused.

Actual result

The focus/caret is placed on the beginning of the second editor content.

When code is run for the second time or if the editor was focused earlier everything works as expected.

Other details (browser, OS, CKEditor version, installed plugins)

Edge (Edge 38.14393, EdgeHTML 14.14393)

This issue causes some unit tests fails in tests/plugins/image2/acf and probably in tests/plugins/image2/justify.