Don't insert redundant BR for merging

Source/core/editing/DeleteSelectionCommand.cpp

 /*
  * Copyright (C) 2005 Apple Computer, Inc.  All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 606 matching lines @@
 
     // m_downstreamEnd's block has been emptied out by deletion.  There is no content inside of it to
     // move, so just remove it.
     Element* endBlock = enclosingBlock(m_downstreamEnd.deprecatedNode());
     if (!endBlock || !endBlock->contains(startOfParagraphToMove.deepEquivalent().deprecatedNode()) || !startOfParagraphToMove.deepEquivalent().deprecatedNode()) {
         removeNode(enclosingBlock(m_downstreamEnd.deprecatedNode()));
         return;
     }
 
     // We need to merge into m_upstreamStart's block, but it's been emptied out and collapsed by deletion.
-    if (!mergeDestination.deepEquivalent().deprecatedNode() || !mergeDestination.deepEquivalent().deprecatedNode()->isDescendantOf(enclosingBlock(m_upstreamStart.containerNode())) || m_startsAtEmptyLine) {
+    if (!mergeDestination.deepEquivalent().deprecatedNode() || (!mergeDestination.deepEquivalent().deprecatedNode()->isDescendantOf(enclosingBlock(m_upstreamStart.containerNode())) && (!mergeDestination.deepEquivalent().anchorNode()->firstChild() || !m_upstreamStart.containerNode()->firstChild())) || (m_startsAtEmptyLine && mergeDestination != startOfParagraphToMove)) {
         insertNodeAt(createBreakElement(document()).get(), m_upstreamStart);
         mergeDestination = VisiblePosition(m_upstreamStart);
     }
 
     if (mergeDestination == startOfParagraphToMove)
         return;
 
     VisiblePosition endOfParagraphToMove = endOfParagraph(startOfParagraphToMove);
 
     if (mergeDestination == endOfParagraphToMove)
@@ skipping 213 matching lines @@
 
 // Normally deletion doesn't preserve the typing style that was present before it.  For example,
 // type a character, Bold, then delete the character and start typing.  The Bold typing style shouldn't
 // stick around.  Deletion should preserve a typing style that *it* sets, however.
 bool DeleteSelectionCommand::preservesTypingStyle() const
 {
     return m_typingStyle;
 }
 
 } // namespace WebCore