Introduce previousPositionOf() for VisiblePosition

Source/core/editing/spellcheck/SpellChecker.cpp

 /*
  * Copyright (C) 2006, 2007, 2008, 2011 Apple Inc. All rights reserved.
  * Copyright (C) 2008 Nokia Corporation and/or its subsidiary(-ies)
  *
  * 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 161 matching lines @@
     VisibleSelection selection(frame().selection().selection());
     Position spellingSearchStart, spellingSearchEnd;
     Range::selectNodeContents(frame().document(), spellingSearchStart, spellingSearchEnd);
 
     bool startedWithSelection = false;
     if (selection.start().anchorNode()) {
         startedWithSelection = true;
         if (startBeforeSelection) {
             VisiblePosition start(selection.visibleStart());
             // We match AppKit's rule: Start 1 character before the selection.
-            VisiblePosition oneBeforeStart = start.previous();
+            VisiblePosition oneBeforeStart = previousPositionOf(start);
             spellingSearchStart = (oneBeforeStart.isNotNull() ? oneBeforeStart : start).toParentAnchoredPosition();
         } else {
             spellingSearchStart = selection.visibleEnd().toParentAnchoredPosition();
         }
     }
 
     Position position = spellingSearchStart;
     if (!isEditablePosition(position)) {
         // This shouldn't happen in very often because the Spelling menu items aren't enabled unless the
         // selection is editable.
         // This can happen in Mail for a mix of non-editable and editable content (like Stationary),
         // when spell checking the whole document before sending the message.
         // In that case the document might not be editable, but there are editable pockets that need to be spell checked.
 
         position = firstEditableVisiblePositionAfterPositionInRoot(position, frame().document()->documentElement()).deepEquivalent();
         if (position.isNull())
             return;
 
         spellingSearchStart = position.parentAnchoredEquivalent();
         startedWithSelection = false; // won't need to wrap
     }
 
     // topNode defines the whole range we want to operate on
     ContainerNode* topNode = highestEditableRoot(position);
     // TODO(yosin): |lastOffsetForEditing()| is wrong here if
     // |editingIgnoresContent(highestEditableRoot())| returns true, e.g. <table>
     spellingSearchEnd = Position::editingPositionOf(topNode, EditingStrategy::lastOffsetForEditing(topNode));
 
-    // If spellingSearchRange starts in the middle of a word, advance to the next word so we start checking
-    // at a word boundary. Going back by one char and then forward by a word does the trick.
+    // If spellingSearchRange starts in the middle of a word, advance to the
+    // next word so we start checking at a word boundary. Going back by one char
+    // and then forward by a word does the trick.
     if (startedWithSelection) {
-    VisiblePosition oneBeforeStart = VisiblePosition(spellingSearchStart).previous();
+    VisiblePosition oneBeforeStart = previousPositionOf(VisiblePosition(spellingSearchStart));
         if (oneBeforeStart.isNotNull())
             spellingSearchStart = endOfWord(oneBeforeStart).toParentAnchoredPosition();
         // else we were already at the start of the editable node
     }
 
     if (spellingSearchStart == spellingSearchEnd)
         return; // nothing to search in
 
     // We go to the end of our first range instead of the start of it, just to be sure
     // we don't get foiled by any word boundary problems at the start. It means we might
@@ skipping 712 matching lines @@
     m_spellCheckRequester->requestCheckingFor(SpellCheckRequest::create(TextCheckingTypeSpelling | TextCheckingTypeGrammar, TextCheckingProcessBatch, rangeToCheck, rangeToCheck));
 }
 
 DEFINE_TRACE(SpellChecker)
 {
     visitor->trace(m_frame);
     visitor->trace(m_spellCheckRequester);
 }
 
 } // namespace blink