Fix for CSS identifier related assert

Source/core/css/parser/BisonCSSParser-in.cpp

 /*
  * Copyright (C) 2003 Lars Knoll (knoll@kde.org)
  * Copyright (C) 2005 Allan Sandfeld Jensen (kde@carewolf.com)
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011, 2012 Apple Inc. All rights reserved.
  * Copyright (C) 2007 Nicholas Shanks <webkit@nickshanks.com>
  * Copyright (C) 2008 Eric Seidel <eric@webkit.org>
  * Copyright (C) 2009 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.com/)
  * Copyright (C) 2012 Adobe Systems Incorporated. All rights reserved.
  * Copyright (C) 2012 Intel Corporation. All rights reserved.
  *
@@ skipping 1765 matching lines @@
     if (charactersAreAllASCII(input, length)) {
         // Fast case for all-ASCII.
         for (unsigned i = 0; i < length; i++)
             output[i] = toASCIILower(input[i]);
     } else {
         for (unsigned i = 0; i < length; i++)
             output[i] = Unicode::toLower(input[i]);
     }
 }
 
-void BisonCSSParser::tokenToLowerCase(const CSSParserString& token)
+void BisonCSSParser::tokenToLowerCase(CSSParserString& token)
 {
     size_t length = token.length();
-    if (m_tokenizer.is8BitSource()) {
-        size_t offset = token.characters8() - m_tokenizer.m_dataStart8.get();
-        makeLower(token.characters8(), m_tokenizer.m_dataStart8.get() + offset, length);
+    if (token.is8Bit()) {
+        makeLower(token.characters8(), const_cast<LChar*>(token.characters8()), length);
     } else {
-        size_t offset = token.characters16() - m_tokenizer.m_dataStart16.get();
-        makeLower(token.characters16(), m_tokenizer.m_dataStart16.get() + offset, length);
+        makeLower(token.characters16(), const_cast<UChar*>(token.characters16()), length);

[rune, 2014/04/02 11:11:09]

Excuse my unicode ignorance, but are you guaranteed that upper/lower case
variants use the same number of code units?

     }
 }
 
 void BisonCSSParser::endInvalidRuleHeader()
 {
     if (m_ruleHeaderType == CSSRuleSourceData::UNKNOWN_RULE)
         return;
 
     CSSParserLocation location;
     location.lineNumber = m_tokenizer.m_lineNumber;
@@ skipping 379 matching lines @@
     rule->setProperties(createStylePropertySet());
     clearProperties();
 
     StyleRuleViewport* result = rule.get();
     m_parsedRules.append(rule.release());
 
     return result;
 }
 
 }