Bug 1637822 [wpt PR 23585] - Add inset inline properties tests for dialog centering tests, a=testonly

Automatic update from web-platform-tests
Add inset inline properties tests for dialog centering tests

--

wpt-commits: 2616c9d6e9e31c3ed90c3682fa8ff71f4b4b429a
wpt-pr: 23585

testing/web-platform/tests/html/semantics/interactive-elements/the-dialog-element/centering.html

@@ -42,7 +42,19 @@ function testDialogCentering(writingMode, containerWritingMode, dialogWritingMod
     iframe.height = iframeHeight;
     iframe.onload = t.step_func_done(() => {
       const dialog = iframe.contentDocument.querySelector("dialog");
-      assert_equals(iframe.contentWindow.getComputedStyle(dialog)[property], numericValue + "px");
+      const dialogStyle = iframe.contentWindow.getComputedStyle(dialog);
+      assert_equals(dialogStyle[property], numericValue + "px");
+      assert_equals(dialogStyle['inset-inline-start'], "0px");
+      assert_equals(dialogStyle['inset-inline-end'], "0px");
+
+      const dialogWM = dialogWritingMode || containerWritingMode || writingMode || "horizontal-tb";
+      if (dialogWM.startsWith("vertical")) {
+        assert_equals(dialogStyle['top'], "0px");
+        assert_equals(dialogStyle['bottom'], "0px");
+      } else {
+        assert_equals(dialogStyle['left'], "0px");
+        assert_equals(dialogStyle['right'], "0px");
+      }
     });
     document.body.appendChild(iframe);
   }, writingMode + (containerWritingMode ? ` (container ${containerWritingMode})` : "") +