[GeometryInterface] add toJSON() function in DOMQuad

third_party/WebKit/LayoutTests/fast/dom/geometry-interface-dom-quad.html

Index: third_party/WebKit/LayoutTests/fast/dom/geometry-interface-dom-quad.html
diff --git a/third_party/WebKit/LayoutTests/fast/dom/geometry-interface-dom-quad.html b/third_party/WebKit/LayoutTests/fast/dom/geometry-interface-dom-quad.html
index 2ffb2b7f0f90c0174b1a203efd12af970e06e43b..071ba7ffa1cf69c0e73f9da3e05296892bf8b8fa 100644
--- a/third_party/WebKit/LayoutTests/fast/dom/geometry-interface-dom-quad.html
+++ b/third_party/WebKit/LayoutTests/fast/dom/geometry-interface-dom-quad.html
@@ -15,4 +15,16 @@ test(() => {
   assert_dom_point_equals(quad.p4, p4);
 }, "DOMQuad() constructor");
 
+test(() => {
+  var p1 = new DOMPoint(0, 1, 3, 4);
+  var p2 = new DOMPoint(5, 6, 7, 8);
+  var p3 = new DOMPoint(9, 10, 11, 12);
+  var p4 = new DOMPoint(13, 14, 15, 16);
+  var quad = new DOMQuad(p1, p2, p3, p4);
+  assert_dom_point_equals(quad.toJSON().p1, p1, "p1");
+  assert_dom_point_equals(quad.toJSON().p2, p2, "p2");
+  assert_dom_point_equals(quad.toJSON().p3, p3, "p3");
+  assert_dom_point_equals(quad.toJSON().p4, p4, "p4");
+}, "DOMQuad() toJSON()");
+
 </script>