When saving the selection, only append the selection end mark to the end of the
container if the following statements are met:
* container is not text
* the offset is not 0 (that would be when the selection starts/end in the
beginning of node)
* offset is bigger by one than the count of the container's children that are
elements
For more see https://developer.mozilla.org/en-US/docs/Web/API/Range/endOffset
In the next cycle we really need to simplify the logic inside the
e_editor_dom_selection_save()..
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