Editing: isVisuallyEquivalentCandidate() should return false for Position with Document.

third_party/WebKit/Source/core/editing/VisibleUnits.cpp

 /*
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009 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 2771 matching lines @@
         return false;
     }
 
     if (isDisplayInsideTable(anchorNode) || Strategy::editingIgnoresContent(anchorNode)) {
         if (!position.atFirstEditingPositionForNode() && !position.atLastEditingPositionForNode())
             return false;
         const Node* parent = Strategy::parent(*anchorNode);
         return parent->layoutObject() && parent->layoutObject()->isSelectable();
     }
 
-    if (anchorNode->document().documentElement() == anchorNode)
+    if (anchorNode->document().documentElement() == anchorNode || anchorNode->isDocumentNode())
         return false;
 
     if (!layoutObject->isSelectable())
         return false;
 
     if (layoutObject->isLayoutBlockFlow() || layoutObject->isFlexibleBox() || layoutObject->isLayoutGrid()) {
         if (toLayoutBlock(layoutObject)->logicalHeight() || isHTMLBodyElement(*anchorNode)) {
             if (!hasRenderedNonAnonymousDescendantsWithHeight(layoutObject))
                 return position.atFirstEditingPositionForNode();
             return anchorNode->hasEditableStyle() && atEditingBoundary(position);
@@ skipping 547 matching lines @@
 {
     return previousPositionOfAlgorithm<EditingStrategy>(visiblePosition, rule);
 }
 
 VisiblePositionInComposedTree previousPositionOf(const VisiblePositionInComposedTree& visiblePosition, EditingBoundaryCrossingRule rule)
 {
     return previousPositionOfAlgorithm<EditingInComposedTreeStrategy>(visiblePosition, rule);
 }
 
 } // namespace blink