Do refactor in collectGradientAttributes() and renderStyleForLengthResolve()

Source/core/svg/SVGLengthContext.cpp

 /*
  * Copyright (C) 2004, 2005, 2006 Nikolas Zimmermann <zimmermann@kde.org>
  * Copyright (C) 2004, 2005, 2006, 2007 Rob Buis <buis@kde.org>
  * Copyright (C) 2007 Apple Inc. All rights reserved.
  * Copyright (C) Research In Motion Limited 2011. 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
  * version 2 of the License, or (at your option) any later version.
@@ skipping 199 matching lines @@
     ASSERT_NOT_REACHED();
     return 0;
 }
 
 static inline RenderStyle* renderStyleForLengthResolving(const SVGElement* context)
 {
     if (!context)
         return 0;
 
     const ContainerNode* currentContext = context;
-    while (currentContext) {
+    do {
         if (currentContext->renderer())
             return currentContext->renderer()->style();
         currentContext = currentContext->parentNode();
-    }
+    } while (currentContext);
 
     // There must be at least a RenderSVGRoot renderer, carrying a style.
     ASSERT_NOT_REACHED();
     return 0;
 }
 
 float SVGLengthContext::convertValueFromUserUnitsToEMS(float value, ExceptionState& exceptionState) const
 {
     RenderStyle* style = renderStyleForLengthResolving(m_context);
     if (!style) {
@@ skipping 77 matching lines @@
 
     const SVGSVGElement* svg = toSVGSVGElement(viewportElement);
     viewportSize = svg->currentViewBoxRect().size();
     if (viewportSize.isEmpty())
         viewportSize = svg->currentViewportSize();
 
     return true;
 }
 
 }