Get rid of redundant member function PositionAlgorithm<Strategy>::{upstream,downstream}

Source/core/editing/commands/ApplyBlockElementCommand.cpp

 /*
  * Copyright (C) 2006, 2008 Apple Inc. All rights reserved.
  * Copyright (C) 2010 Google 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
@@ skipping 92 matching lines @@
         VisiblePosition end(visiblePositionForIndex(endIndex, endScope.get()));
         if (start.isNotNull() && end.isNotNull())
             setEndingSelection(VisibleSelection(start, end, endingSelection().isDirectional()));
     }
 }
 
 void ApplyBlockElementCommand::formatSelection(const VisiblePosition& startOfSelection, const VisiblePosition& endOfSelection)
 {
     // Special case empty unsplittable elements because there's nothing to split
     // and there's nothing to move.
-    Position start = startOfSelection.deepEquivalent().downstream();
+    Position start = mostForwardCaretPosition(startOfSelection.deepEquivalent());
     if (isAtUnsplittableElement(start)) {
         RefPtrWillBeRawPtr<HTMLElement> blockquote = createBlockElement();
         insertNodeAt(blockquote, start);
         RefPtrWillBeRawPtr<HTMLBRElement> placeholder = createBreakElement(document());
         appendNode(placeholder, blockquote);
         setEndingSelection(VisibleSelection(positionBeforeNode(placeholder.get()), TextAffinity::Downstream, endingSelection().isDirectional()));
         return;
     }
 
     RefPtrWillBeRawPtr<HTMLElement> blockquoteForNextIndent = nullptr;
@@ skipping 170 matching lines @@
     return element.release();
 }
 
 DEFINE_TRACE(ApplyBlockElementCommand)
 {
     visitor->trace(m_endOfLastParagraph);
     CompositeEditCommand::trace(visitor);
 }
 
 }