Rewrite the layout test for DOMRect interface.

third_party/WebKit/LayoutTests/fast/dom/resources/geometry-interfaces-test-helpers.js

 function assert_identity_2d_matrix(actual) {
   assert_true(actual instanceof DOMMatrixReadOnly);
   assert_true(actual.is2D, "is2D");
   assert_true(actual.isIdentity, "isIdentity");
   assert_identity_matrix(actual);
 }
 
 function assert_identity_3d_matrix(actual) {
   assert_true(actual instanceof DOMMatrixReadOnly);
   assert_false(actual.is2D, "is2D");
@@ skipping 62 matching lines @@
     assert_equals(actual.z, expected[2], "point equality: z differs");
     assert_equals(actual.w, expected[3], "point equality: w differs");
   } else if(expected instanceof DOMPointReadOnly) {
     assert_equals(actual.x, expected.x, "point equality: x differs");
     assert_equals(actual.y, expected.y, "point equality: y differs");
     assert_equals(actual.z, expected.z, "point equality: z differs");
     assert_equals(actual.w, expected.w, "point equality: w differs");
   } else {
     assert_unreached();
   }
+}
+ 
+function assert_dom_rect_equals(actual, expected) {
+  assert_true(actual instanceof DOMRectReadOnly);
+  if(Array.isArray(expected)) {
+    assert_equals(expected.length, 8);
+    assert_equals(actual.x, expected[0], "rect equality: x differs");
+    assert_equals(actual.y, expected[1], "rect equality: y differs");
+    assert_equals(actual.width, expected[2], "rect equality: width differs");
+    assert_equals(actual.height, expected[3], "rect equality: height differs");
+    assert_equals(actual.top, expected[4], "rect equality: top differs");
+    assert_equals(actual.right, expected[5], "rect equality: right differs");
+    assert_equals(actual.bottom, expected[6], "rect equality: bottom differs");
+    assert_equals(actual.left, expected[7], "rect equality: left differs");
+  } else if(expected instanceof DOMRectReadOnly) {
+    assert_equals(actual.x, expected.x, "rect equality: x differs");
+    assert_equals(actual.y, expected.y, "rect equality: y differs");
+    assert_equals(actual.width, expected.width, "rect equality: width differs");
+    assert_equals(actual.height, expected.height, "rect equality: height differs");
+    assert_equals(actual.top, expected.top, "rect equality: top differs");
+    assert_equals(actual.right, expected.right, "rect equality: right differs");
+    assert_equals(actual.bottom, expected.bottom, "rect equality: bottom differs");
+    assert_equals(actual.left, expected.left, "poirectnt equality: left differs");
+  } else {
+    assert_unreached();
+  }
 }