Editor insertion methods may leave empty spans for selection over multiple block elements

[f1ames]

Type of report

Bug

Provide detailed reproduction steps (if any)

Related to #2813 and extracted from #2987 (review).

1. Go to https://codepen.io/f1ames/pen/agZQjW.
2. Fully select more than one red-bordered element.
3. Use one of the Insert ... button under editor (apart from Insert text).

Expected result

Text div is inserted, no empty red-bordered elements left.

Actual result

Text div is inserted, one/two empty red-bordered elements left.

May be somehow related to #3175 (or some of its subcases).

Other details

• Browser: All
• OS: All
• CKEditor version: 4.5+ (4.5 is the oldest one I have checked)
• Installed CKEditor plugins: any