Incorrectly wrapped content when pasting into editor with enter div mode

[jacekbogdanski]

Type of report

Bug

Provide detailed reproduction steps (if any)

This is a follow-up issue to #2751.

When working on #4301 we find out that the issue described in #2751 still exists if a selection is done by mouse, not ctrl + a keyboard shortcut.

1. Open tests/core/editable/manual/enterdiv manual test.
2. Reproduce test steps, but select all editor content using mouse, not keyboard.

Also, see #4356 (comment) for more information on the issue.

Expected result

Test passes.

Actual result

div wrapping element is duplicated in some test cases

Other details

• Browser: all
• CKEditor version: 4.16.1
• Installed CKEditor plugins: enterkey