Remove document param from parseSystemColor

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 1106 matching lines @@
 
 bool BisonCSSParser::parseColor(const String& string)
 {
     setupParser("@-internal-decls color:", string, "");
     cssyyparse(this);
     m_rule = nullptr;
 
     return !m_parsedProperties.isEmpty() && m_parsedProperties.first().id() == CSSPropertyColor;
 }
 
-bool BisonCSSParser::parseSystemColor(RGBA32& color, const String& string, Document* document)
+bool BisonCSSParser::parseSystemColor(RGBA32& color, const String& string)
 {
-    if (!document)
-        return false;
-
     CSSParserString cssColor;
     cssColor.init(string);
     CSSValueID id = cssValueKeywordID(cssColor);
     if (!CSSPropertyParser::isSystemColor(id))
         return false;
 
     Color parsedColor = RenderTheme::theme().systemColor(id);
     color = parsedColor.rgb();
     return true;
 }
@@ skipping 1077 matching lines @@
     rule->setProperties(createStylePropertySet());
     clearProperties();
 
     StyleRuleViewport* result = rule.get();
     m_parsedRules.append(rule.release());
 
     return result;
 }
 
 }