Handle special case of merging lists in mergeParagraphs()

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 ce27bb711cf0898ce1eb7760c9b3a2d8e635bdc6..0630c426309a9c1f03d1dc46cdcdcbf0c45e9e74 100644
--- a/Source/core/editing/DeleteSelectionCommand.cpp
+++ b/Source/core/editing/DeleteSelectionCommand.cpp
@@ -639,6 +639,17 @@ void DeleteSelectionCommand::mergeParagraphs()
     if (mergeDestination == endOfParagraphToMove)
         return;
 
+    // If the merge destination and source to be moved are both list items of different lists, merge them into single list.
+    Node* listItemInFirstParagraph = enclosingNodeOfType(m_upstreamStart, &isListItem);

[yosin_UTC9, 2013/12/12 04:20:45]

nit: You don't need to have "&" for isListItem.

+    Node* listItemInSecondParagraph = enclosingNodeOfType(m_downstreamEnd, &isListItem);

[yosin_UTC9, 2013/12/12 04:20:45]

nit: You don't need to have "&" for isListItem.

+    if (listItemInFirstParagraph && listItemInSecondParagraph

[yosin_UTC9, 2013/12/12 04:20:45]

ni: Can we merge if-conditions of L645 and L647?

+        && listItemInFirstParagraph->parentElement() != listItemInSecondParagraph->parentElement()) {
+        if (canMergeLists(listItemInFirstParagraph->parentElement(), listItemInSecondParagraph->parentElement())) {
+            mergeIdenticalElements(listItemInFirstParagraph->parentElement(), listItemInSecondParagraph->parentElement());
+            return;
+        }
+    }
+
     // The rule for merging into an empty block is: only do so if its farther to the right.
     // FIXME: Consider RTL.
     if (!m_startsAtEmptyLine && isStartOfParagraph(mergeDestination) && startOfParagraphToMove.absoluteCaretBounds().x() > mergeDestination.absoluteCaretBounds().x()) {