Introduce isVisuallyEquivalentCandidate() as replacement of PositionAlgorithm::isCandidate()

Source/core/editing/commands/InsertParagraphSeparatorCommand.cpp

 /*
  * Copyright (C) 2005, 2006 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 166 matching lines @@
         || isHTMLFormElement(*startBlock)
         // FIXME: If the node is hidden, we don't have a canonical position so we will do the wrong thing for tables and <hr>. https://bugs.webkit.org/show_bug.cgi?id=40342
         || (!canonicalPos.isNull() && isRenderedTableElement(canonicalPos.anchorNode()))
         || (!canonicalPos.isNull() && isHTMLHRElement(*canonicalPos.anchorNode()))) {
         applyCommandToComposite(InsertLineBreakCommand::create(document()));
         return;
     }
 
     // Use the leftmost candidate.
     insertionPosition = insertionPosition.upstream();
-    if (!insertionPosition.isCandidate())
+    if (!isVisuallyEquivalentCandidate(insertionPosition))
         insertionPosition = insertionPosition.downstream();
 
     // Adjust the insertion position after the delete
     insertionPosition = positionAvoidingSpecialElementBoundary(insertionPosition);
     VisiblePosition visiblePos(insertionPosition, affinity);
     calculateStyleBeforeInsertion(insertionPosition);
 
     //---------------------------------------------------------------------
     // Handle special case of typing return on an empty list item
     if (breakOutOfEmptyListItem())
@@ skipping 235 matching lines @@
 }
 
 DEFINE_TRACE(InsertParagraphSeparatorCommand)
 {
     visitor->trace(m_style);
     CompositeEditCommand::trace(visitor);
 }
 
 
 } // namespace blink