Add a version of SVGLengthContext::valueForLength with explicit dimension

Source/core/svg/SVGLengthContext.cpp

Index: Source/core/svg/SVGLengthContext.cpp
diff --git a/Source/core/svg/SVGLengthContext.cpp b/Source/core/svg/SVGLengthContext.cpp
index 4f229d37b1ff000f0601d32346b4a59b73e4cd05..13c8784f7473ca59b853d36378192259f97b00fa 100644
--- a/Source/core/svg/SVGLengthContext.cpp
+++ b/Source/core/svg/SVGLengthContext.cpp
@@ -98,20 +98,21 @@ float SVGLengthContext::resolveLength(const SVGElement* context, SVGUnitTypes::S
 
 float SVGLengthContext::valueForLength(const Length& length, const LayoutStyle& style, SVGLengthMode mode) const
 {
-    return valueForLengthWithZoom(length, style.effectiveZoom(), mode);
-}
-
-float SVGLengthContext::valueForLengthWithZoom(const Length& length, float zoom, SVGLengthMode mode) const
-{
-    ASSERT(zoom != 0);
     float dimension = 0;
     if (length.isPercent()) {
         FloatSize viewportSize;
         determineViewport(viewportSize);
         // The viewport will be unaffected by zoom.
-        dimension = dimensionForLengthMode(mode, viewportSize) * zoom;
+        dimension = dimensionForLengthMode(mode, viewportSize);
     }
-    return floatValueForLength(length, dimension) / zoom;
+    return valueForLength(length, style, dimension);
+}
+
+float SVGLengthContext::valueForLength(const Length& length, const LayoutStyle& style, float dimension)
+{
+    const float zoom = style.effectiveZoom();
+    ASSERT(zoom != 0);
+    return floatValueForLength(length, dimension * zoom) / zoom;
 }
 
 float SVGLengthContext::convertValueToUserUnits(float value, SVGLengthMode mode, SVGLengthType fromUnit) const