canMergeLists() should make sure that the list items do not belong to the same list

Source/core/editing/DeleteSelectionCommand.cpp

Index: Source/core/editing/DeleteSelectionCommand.cpp
diff --git a/Source/core/editing/DeleteSelectionCommand.cpp b/Source/core/editing/DeleteSelectionCommand.cpp
index de814092d875265882ff4096cb7ef045a27687ec..160e346f1f6ba6f34158cee435e234f3d70e5871 100644
--- a/Source/core/editing/DeleteSelectionCommand.cpp
+++ b/Source/core/editing/DeleteSelectionCommand.cpp
@@ -635,6 +635,7 @@ void DeleteSelectionCommand::mergeParagraphs()
     Node* listItemInFirstParagraph = enclosingNodeOfType(m_upstreamStart, isListItem);
     Node* listItemInSecondParagraph = enclosingNodeOfType(m_downstreamEnd, isListItem);
     if (listItemInFirstParagraph && listItemInSecondParagraph
+        && listItemInFirstParagraph->parentElement() != listItemInSecondParagraph->parentElement()
         && canMergeLists(listItemInFirstParagraph->parentElement(), listItemInSecondParagraph->parentElement())) {
         mergeIdenticalElements(listItemInFirstParagraph->parentElement(), listItemInSecondParagraph->parentElement());
         m_endingPosition = mergeDestination.deepEquivalent();