Move create() methods from StylePropertySet to MutableStylePropertySet.

Source/core/html/canvas/CanvasRenderingContext2D.cpp

 /*
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011, 2012 Apple Inc. All rights reserved.
  * Copyright (C) 2008, 2010 Nokia Corporation and/or its subsidiary(-ies)
  * Copyright (C) 2007 Alp Toker <alp@atoker.com>
  * Copyright (C) 2008 Eric Seidel <eric@webkit.org>
  * Copyright (C) 2008 Dirk Schulze <krit@webkit.org>
  * Copyright (C) 2010 Torch Mobile (Beijing) Co. Ltd. All rights reserved.
  * Copyright (C) 2012 Intel Corporation. All rights reserved.
  * Copyright (C) 2013 Adobe Systems Incorporated. All rights reserved.
  *
@@ skipping 1957 matching lines @@
     }
 
     return serializedFont.toString();
 }
 
 void CanvasRenderingContext2D::setFont(const String& newFont)
 {
     if (newFont == state().m_unparsedFont && state().m_realizedFont)
         return;
 
-    RefPtr<StylePropertySet> parsedStyle = StylePropertySet::create();
+    RefPtr<MutableStylePropertySet> parsedStyle = MutableStylePropertySet::create();
     CSSParser::parseValue(parsedStyle.get(), CSSPropertyFont, newFont, true, strictToCSSParserMode(!m_usesCSSCompatibilityParseMode), 0);
     if (parsedStyle->isEmpty())
         return;
 
     String fontValue = parsedStyle->getPropertyValue(CSSPropertyFont);
 
     // According to http://lists.w3.org/Archives/Public/public-html/2009Jul/0947.html,
     // the "inherit" and "initial" values must be ignored.
     if (fontValue == "inherit" || fontValue == "initial")
         return;
@@ skipping 261 matching lines @@
 }
 
 PassRefPtr<Canvas2DContextAttributes> CanvasRenderingContext2D::getContextAttributes() const
 {
     RefPtr<Canvas2DContextAttributes> attributes = Canvas2DContextAttributes::create();
     attributes->setAlpha(m_hasAlpha);
     return attributes.release();
 }
 
 } // namespace WebCore