Avoid adding placeholder when deleting last text in root

Source/core/editing/CompositeEditCommand.cpp

 /*
  * Copyright (C) 2005, 2006, 2007, 2008 Apple 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 1032 matching lines @@
 // empty or unrendered parents).
 
 void CompositeEditCommand::cleanupAfterDeletion(VisiblePosition destination)
 {
     VisiblePosition caretAfterDelete = endingSelection().visibleStart();
     Node* destinationNode = destination.deepEquivalent().anchorNode();
     if (caretAfterDelete != destination && isStartOfParagraph(caretAfterDelete) && isEndOfParagraph(caretAfterDelete)) {
         // Note: We want the rightmost candidate.
         Position position = caretAfterDelete.deepEquivalent().downstream();
         Node* node = position.deprecatedNode();
+
+        // Bail if we'd remove an ancestor of our destination.

[yosin_UTC9, 2013/07/12 01:55:28]

Could you move this change in another CL? I think this change doesn't relate to
avoid adding placeholder. It seems more tests affected than original patch.

This change may change behavior, existing test failures reveal. I may try this,
but not sure...

+        if (destinationNode->isDescendantOf(node))
+            return;
+
         // Normally deletion will leave a br as a placeholder.
-        if (node->hasTagName(brTag))
+        if (node->hasTagName(brTag)) {
             removeNodeAndPruneAncestors(node, destinationNode);
-        // If the selection to move was empty and in an empty block that 
-        // doesn't require a placeholder to prop itself open (like a bordered
-        // div or an li), remove it during the move (the list removal code
-        // expects this behavior).
-        else if (isBlock(node)) {
+
+            // If the selection to move was empty and in an empty block that
+            // doesn't require a placeholder to prop itself open (like a bordered
+            // div or an li), remove it during the move (the list removal code
+            // expects this behavior).
+        } else if (isBlock(node)) {
             // If caret position after deletion and destination position coincides,
             // node should not be removed.
             if (!position.rendersInDifferentPosition(destination.deepEquivalent())) {
                 prune(node, destinationNode);
                 return;
             }
             removeNodeAndPruneAncestors(node, destinationNode);
         }
         else if (lineBreakExistsAtPosition(position)) {
             // There is a preserved '\n' at caretAfterDelete.
@@ skipping 387 matching lines @@
     return node.release();
 }
 
 PassRefPtr<Element> createBlockPlaceholderElement(Document* document)
 {
     RefPtr<Element> breakNode = document->createElement(brTag, false);
     return breakNode.release();
 }
 
 } // namespace WebCore