Introduce firstRangeOf() as replacement of VisibleSelection::firstRange()

Source/core/editing/VisibleSelection.cpp

 /*
  * Copyright (C) 2004, 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 198 matching lines @@
 PositionInComposedTree VisibleSelection::startInComposedTree() const
 {
     return m_startInComposedTree;
 }
 
 PositionInComposedTree VisibleSelection::endInComposedTree() const
 {
     return m_endInComposedTree;
 }
 
-PassRefPtrWillBeRawPtr<Range> VisibleSelection::firstRange() const
+PassRefPtrWillBeRawPtr<Range> firstRangeOf(const VisibleSelection& selection)
 {
-    if (isNone())
+    if (selection.isNone())
         return nullptr;
-    Position start = m_start.parentAnchoredEquivalent();
-    Position end = m_end.parentAnchoredEquivalent();
+    Position start = selection.start().parentAnchoredEquivalent();
+    Position end = selection.end().parentAnchoredEquivalent();
     return Range::create(*start.document(), start, end);
 }
 
 bool VisibleSelection::intersectsNode(Node* node) const
 {
     if (isNone())
         return false;
     Position start = m_start.parentAnchoredEquivalent();
     Position end = m_end.parentAnchoredEquivalent();
     TrackExceptionState exceptionState;
@@ skipping 1009 matching lines @@
     sel.showTreeForThis();
 }
 
 void showTree(const blink::VisibleSelection* sel)
 {
     if (sel)
         sel->showTreeForThis();
 }
 
 #endif