Optimize SelectorChecker's containsHTMLSpace() utility function

Source/core/css/SelectorChecker.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 2004-2005 Allan Sandfeld Jensen (kde@carewolf.com)
  * Copyright (C) 2006, 2007 Nicholas Shanks (webkit@nickshanks.com)
  * Copyright (C) 2005, 2006, 2007, 2008, 2009, 2010, 2011, 2012, 2013 Apple Inc. All rights reserved.
  * Copyright (C) 2007 Alexey Proskuryakov <ap@webkit.org>
  * Copyright (C) 2007, 2008 Eric Seidel <eric@webkit.org>
  * Copyright (C) 2008, 2009 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.com/)
  * Copyright (c) 2011, Code Aurora Forum. All rights reserved.
  * Copyright (C) Research In Motion Limited 2011. All rights reserved.
@@ skipping 389 matching lines @@
             nextContext.behaviorAtBoundary = behaviorAtBoundary;
 
         nextContext.isSubSelector = false;
         nextContext.elementStyle = 0;
         if (match(nextContext, siblingTraversalStrategy, result) == SelectorMatches)
             return SelectorMatches;
     }
     return SelectorFailsLocally;
 }
 
+template<typename CharType>
+static inline bool containsHTMLSpaceTemplate(const CharType* string, unsigned length)
+{
+    for (unsigned i = 0; i < length; ++i)
+        if (isHTMLSpace<CharType>(string[i]))
+            return true;
+    return false;
+}
+
 static inline bool containsHTMLSpace(const AtomicString& string)
 {
-    for (unsigned i = 0; i < string.length(); i++)
-        if (isHTMLSpace<UChar>(string[i]))
-            return true;
-    return false;
+    if (LIKELY(string.is8Bit()))
+        return containsHTMLSpaceTemplate<LChar>(string.characters8(), string.length());
+    return containsHTMLSpaceTemplate<UChar>(string.characters16(), string.length());
 }
 
 static bool attributeValueMatches(const Attribute& attributeItem, CSSSelector::Match match, const AtomicString& selectorValue, bool caseSensitive)
 {
     const AtomicString& value = attributeItem.value();
     if (value.isNull())
         return false;
 
     switch (match) {
     case CSSSelector::Exact:
@@ skipping 716 matching lines @@
     return element.focused() && isFrameFocused(element);
 }
 
 template
 SelectorChecker::Match SelectorChecker::match(const SelectorCheckingContext&, const DOMSiblingTraversalStrategy&, MatchResult*) const;
 
 template
 SelectorChecker::Match SelectorChecker::match(const SelectorCheckingContext&, const ShadowDOMSiblingTraversalStrategy&, MatchResult*) const;
 
 }