Use Length for the stroke-width property in SVGLayoutStyle

Source/core/svg/SVGLengthContext.h

Index: Source/core/svg/SVGLengthContext.h
diff --git a/Source/core/svg/SVGLengthContext.h b/Source/core/svg/SVGLengthContext.h
index d17b89d7072a364079bf1e060395085d6ebd1c30..5642edb2db1cab31f98bd28a3cd3fb74db5b08a4 100644
--- a/Source/core/svg/SVGLengthContext.h
+++ b/Source/core/svg/SVGLengthContext.h
@@ -29,6 +29,7 @@ namespace blink {
 class LayoutStyle;
 class SVGElement;
 class SVGLength;
+class UnzoomedLength;
 
 enum SVGLengthType {
     LengthTypeUnknown = 0,
@@ -68,12 +69,16 @@ public:
     float convertValueToUserUnits(float, SVGLengthMode, SVGLengthType fromUnit) const;
     float convertValueFromUserUnits(float, SVGLengthMode, SVGLengthType toUnit) const;
 
+    float valueForLength(const UnzoomedLength&, SVGLengthMode = SVGLengthMode::Other) const;
     float valueForLength(const Length&, const LayoutStyle&, SVGLengthMode = SVGLengthMode::Other) const;
     static float valueForLength(const Length&, const LayoutStyle&, float dimension);
 
     bool determineViewport(FloatSize&) const;
 
 private:
+    float valueForLength(const Length&, float zoom, SVGLengthMode) const;
+    static float valueForLength(const Length&, float zoom, float dimension);
+
     float convertValueFromUserUnitsToEMS(float value) const;
     float convertValueFromEMSToUserUnits(float value) const;