Cleanup Path2D constructor

See https://github.com/whatwg/html/pull/3409.
diff --git a/interfaces/html.idl b/interfaces/html.idl
index 1147666..a6068c0 100644
--- a/interfaces/html.idl
+++ b/interfaces/html.idl
@@ -1376,10 +1376,7 @@
   readonly attribute Uint8ClampedArray data;
 };
 
-[Constructor,
- Constructor(Path2D path),
- Constructor(sequence<Path2D> paths, optional CanvasFillRule fillRule = "nonzero"),
- Constructor(DOMString d),
+[Constructor(optional (Path2D or DOMString) path),
  Exposed=(Window,Worker)]
 interface Path2D {
   void addPath(Path2D path, optional DOMMatrix2DInit transform);