Add number() static methods to AtomicString class

Source/core/html/HTMLElement.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  * Copyright (C) 2004, 2005, 2006, 2007, 2008 Apple Inc. All rights reserved.
  * Copyright (C) 2009 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.com/)
  * Copyright (C) 2011 Motorola Mobility. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
@@ skipping 662 matching lines @@
 
 short HTMLElement::tabIndex() const
 {
     if (supportsFocus())
         return Element::tabIndex();
     return -1;
 }
 
 void HTMLElement::setTabIndex(int value)
 {
-    setAttribute(tabindexAttr, String::number(value));
+    setIntegralAttribute(tabindexAttr, value);
 }
 
 TranslateAttributeMode HTMLElement::translateAttributeMode() const
 {
     const AtomicString& value = getAttribute(translateAttr);
 
     if (value == nullAtom)
         return TranslateAttributeInherit;
     if (equalIgnoringCase(value, "yes") || equalIgnoringCase(value, ""))
         return TranslateAttributeYes;
@@ skipping 378 matching lines @@
 #ifndef NDEBUG
 
 // For use in the debugger
 void dumpInnerHTML(WebCore::HTMLElement*);
 
 void dumpInnerHTML(WebCore::HTMLElement* element)
 {
     printf("%s\n", element->innerHTML().ascii().data());
 }
 #endif