Layout support for new circle shape syntax

Source/core/css/BasicShapeFunctions.cpp

Index: Source/core/css/BasicShapeFunctions.cpp
diff --git a/Source/core/css/BasicShapeFunctions.cpp b/Source/core/css/BasicShapeFunctions.cpp
index 8f948ae8eeb4d49654c17aadd78c4d88f106699e..86cd92ea9e189827cdf850bcada7c3b82feb719f 100644
--- a/Source/core/css/BasicShapeFunctions.cpp
+++ b/Source/core/css/BasicShapeFunctions.cpp
@@ -321,4 +321,23 @@ PassRefPtr<BasicShape> basicShapeForValue(const StyleResolverState& state, const
 
     return basicShape.release();
 }
+
+float floatValueForCenterCoordinate(const BasicShapeCenterCoordinate& center, float boxDimension)
+{
+    float offset = floatValueForLength(center.length(), boxDimension);
+    switch (center.keyword()) {
+    case BasicShapeCenterCoordinate::None:
+        return offset;
+    case BasicShapeCenterCoordinate::Top:
+    case BasicShapeCenterCoordinate::Left:
+        return offset;
+    case BasicShapeCenterCoordinate::Bottom:
+    case BasicShapeCenterCoordinate::Right:
+        return boxDimension - offset;
+    }
+
+    ASSERT_NOT_REACHED();
+    return 0;
+}
+
 }