trimmed release 18.0.1025.162
trimmed release 19.0.1084.52
trimmed release 20.0.1132.47
trimmed release 20.0.1132.57
trimmed release 21.0.1180.60
trimmed release 23.0.1271.97
trimmed release 24.0.1312.52
trimmed release 24.0.1312.56
trimmed release 25.0.1364.84
trimmed release 25.0.1364.152
trimmed release 26.0.1410.33
trimmed release 26.0.1410.43
trimmed release 27.0.1453.73
trimmed release 27.0.1453.94
trimmed release 27.0.1453.110
trimmed release 28.0.1500.95
Avoid deleting nodes that have already been pruned

DRQS 47079091

removeNodeAndPruneAncestors will invalidate startOfParagraphToMove in some
cases, so m_endingPosition must be set to something valid instead.  We try to
set it to m_upstreamStart, but if that has also been removed, then we resort to
the first editable position in the root editable element.
Rebase 'bugfix/dontDeleteAfterPrune' from upstream/26.0.1410.43 onto upstream/28.0.1500.95