Crash in downcast conversion when moving selection between table cells

[oleq]

📝 Provide detailed reproduction steps (if any)

Check out the screencast. I'm attaching everything I did starting from the moment I reloaded the webpage (this may be yet another bugfoot).

Note: I came across this issue when trying to reproduce another one (hence all the noise).

I was testing the Document Editor sample (http://fake.ckeditor.com/ck/5/ckeditor5/build/docs/ckeditor5/latest/examples/builds/document-editor.html)

ckeditorerror.js:70 Uncaught TypeError: element.getCustomProperty(...) is not a function
    at DowncastDispatcher.eval (downcasthelpers.js:1342)
    at DowncastDispatcher.fire (emittermixin.js:218)
    at DowncastDispatcher.convertMarkerRemove (downcastdispatcher.js:391)
    at DowncastDispatcher.convertChanges (downcastdispatcher.js:136)
    at eval (editingcontroller.js:104)
    at View.change (view.js:502)
    at Document.EditingController.listenTo.priority (editingcontroller.js:103)
    at Document.fire (emittermixin.js:218)
    at Document._handleChangeBlock (document.js:331)
    at Model._runPendingChanges (model.js:854)
CKEditorError @ ckeditorerror.js:70
rethrowUnexpectedError @ ckeditorerror.js:122
fire @ emittermixin.js:253
convertMarkerRemove @ downcastdispatcher.js:391
convertChanges @ downcastdispatcher.js:136
eval @ editingcontroller.js:104
change @ view.js:502
EditingController.listenTo.priority @ editingcontroller.js:103
fire @ emittermixin.js:218
_handleChangeBlock @ document.js:331
_runPendingChanges @ model.js:854
change @ model.js:196
_hideFakeVisualSelection @ linkui.js:690
_removeFormView @ linkui.js:395
_hideUI @ linkui.js:464
callback @ linkui.js:303
eval @ clickoutsidehandler.js:45
fire @ emittermixin.js:218
domListener @ emittermixin.js:253

📃 Other details

• Browser: Chrome
• OS: Mac
• CKEditor version: master

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[oleq]

The issue comes down to the following steps (note the backwards selection that ends at the beginning of the previous list item):

[mlewand]

Duplicate of #7907