What replaces SQLServer SQLGeometryBuilder for Windows store apps

Question

Porting Visual Studio 2008 C# application to Visual Studio 2013, Windows 8.1 store\phone app (need to include a DB with the application). What DB to use (coding in c#), to replace this code...

private static double GetArea(SurveySegment[] segments)
{
  SqlGeometryBuilder builder = new SqlGeometryBuilder();
  builder.SetSrid(0); // Don't need an SRID here
  builder.BeginGeometry(OpenGisGeometryType.Polygon);

  // Walk around the segments
  PointF p = new PointF(0, 0);
  builder.BeginFigure(p.X, p.Y);
  for (int i = 0; i < segments.Length; i++)
  {
    p += segments[i].FromOrigin;
    builder.AddLine(p.X, p.Y);
  }

  // Polygon's end point must be at the origin
  if (p.X != 0 || p.Y != 0)
    builder.AddLine(0, 0);

  builder.EndFigure();
  builder.EndGeometry();

  // Return the area in the units used in the segments
  return builder.ConstructedGeometry.STArea().Value;
    }