Fix problems with flakes in SVG LayoutTests by reordering arithmetic.

Source/core/svg/SVGLengthContext.h

 /*
  * 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.
  *
  * This library is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
@@ skipping 54 matching lines @@
     static float resolveLength(const SVGElement*, SVGUnitTypes::SVGUnitType, PassRefPtrWillBeRawPtr<SVGLength>);
 
     float convertValueToUserUnits(float, SVGLengthMode, SVGLengthType fromUnit, ExceptionState&) const;
     float convertValueFromUserUnits(float, SVGLengthMode, SVGLengthType toUnit, ExceptionState&) const;
 
     bool determineViewport(FloatSize&) const;
 
 private:
     float convertValueFromUserUnitsToPercentage(float value, SVGLengthMode, ExceptionState&) const;
     float convertValueFromPercentageToUserUnits(float value, SVGLengthMode, ExceptionState&) const;
-    static float convertValueFromPercentageToUserUnits(float value, SVGLengthMode, const FloatSize&);
+    static float convertValueFromPercentageToUserUnits(float value, SVGLengthMode, const FloatSize& viewportSize);
+    static float convertValueFromPercentageToUserUnits(const SVGLength& value, const FloatSize& viewportSize);
 
     float convertValueFromUserUnitsToEMS(float value, ExceptionState&) const;
     float convertValueFromEMSToUserUnits(float value, ExceptionState&) const;
 
     float convertValueFromUserUnitsToEXS(float value, ExceptionState&) const;
     float convertValueFromEXSToUserUnits(float value, ExceptionState&) const;
 
     RawPtrWillBeMember<const SVGElement> m_context;
 };
 
 } // namespace blink
 
 #endif // SVGLengthContext_h