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

Source/core/editing/commands/EditorCommand.cpp

 /*
  * Copyright (C) 2006, 2007, 2008 Apple Inc. All rights reserved.
  * Copyright (C) 2008 Nokia Corporation and/or its subsidiary(-ies)
  * Copyright (C) 2009 Igalia S.L.
  *
  * 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.
@@ skipping 1418 matching lines @@
 static String valueForeColor(LocalFrame& frame, Event*)
 {
     return valueStyle(frame, CSSPropertyColor);
 }
 
 static String valueFormatBlock(LocalFrame& frame, Event*)
 {
     const VisibleSelection& selection = frame.selection().selection();
     if (!selection.isNonOrphanedCaretOrRange() || !selection.isContentEditable())
         return "";
-    Element* formatBlockElement = FormatBlockCommand::elementForFormatBlockCommand(selection.firstRange().get());
+    Element* formatBlockElement = FormatBlockCommand::elementForFormatBlockCommand(firstRangeOf(selection).get());
     if (!formatBlockElement)
         return "";
     return formatBlockElement->localName();
 }
 
 // Map of functions
 
 struct CommandEntry {
     const char* name;
     EditorInternalCommand command;
@@ skipping 341 matching lines @@
 {
     return m_command && m_command->isTextInsertion;
 }
 
 int Editor::Command::idForHistogram() const
 {
     return isSupported() ? m_command->idForUserMetrics : 0;
 }
 
 } // namespace blink