Adding matrixTrasnform to DOMPointReadOnly interfaces as following spec.

third_party/WebKit/LayoutTests/fast/dom/geometry-interfaces-dom-point-readonly.html

Index: third_party/WebKit/LayoutTests/fast/dom/geometry-interfaces-dom-point-readonly.html
diff --git a/third_party/WebKit/LayoutTests/fast/dom/geometry-interfaces-dom-point-readonly.html b/third_party/WebKit/LayoutTests/fast/dom/geometry-interfaces-dom-point-readonly.html
index 1c0ef51af372df8bb0a97628baff50241830431e..a3e341b0f06cec5e5ea96d60293478702d1508bd 100644
--- a/third_party/WebKit/LayoutTests/fast/dom/geometry-interfaces-dom-point-readonly.html
+++ b/third_party/WebKit/LayoutTests/fast/dom/geometry-interfaces-dom-point-readonly.html
@@ -40,10 +40,19 @@ test(() => {
   var point1 = DOMPointReadOnly.fromPoint();
   var point2 = DOMPointReadOnly.fromPoint();
   assert_false(point1 == point2);
-  assert_true(point1.x == point2.x);
-  assert_true(point1.y == point2.y);
-  assert_true(point1.z == point2.z);
-  assert_true(point1.w == point2.w);
+  assert_point_equals(point1, point2);
 }, 'DOMPointReadOnly.fromPoint() should create a new DOMPointReadOnly');
 
+test(() => {
+  var point1 = new DOMPointReadOnly(5, 4, 0, 1);

[zino, 2016/12/28 16:39:14]

var point = new DOMPointReadOnly(5, 4);

[Byoungkwon Ko, 2017/01/03 15:54:37]

Done.

+  var point2 = point1.matrixTransform(new DOMMatrixReadOnly([2, 0, 0, 2, 10, 10]));

[zino, 2016/12/28 16:39:14]

nit: Better name is transformed_point.

[Byoungkwon Ko, 2017/01/03 15:54:37]

Done.

+  assert_point_equals(point2, new DOMPoint(20, 18));

[zino, 2016/12/28 16:39:14]

You used |assert_dom_point_equals| in previous CL. The function takes array as
expected argument, right?
But you are using |assert_point_equals| in this CL. The function takes object
instead of array as expected argument.
It's so confusing to me. I think you can merge two functions. Could you follow
it up? (and use it?)

[Byoungkwon Ko, 2017/01/03 15:54:37]

Done.

+}, 'DOMMatrixReadOnly.matrixTransform() - 2d matrixTransform');
+
+test(() => {
+  var point1 = new DOMPointReadOnly(5, 4, 0, 1);
+  var point2 = point1.matrixTransform(new DOMMatrixReadOnly([1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16]));
+  assert_point_equals(point2, new DOMPoint(38, 48, 58, 68));
+}, 'DOMMatrixReadOnly.matrixTransform() - 3d matrixTransform');
+
 </script>