Auto merge of #23203 - iulianR:22828, r=jdm

Implement PerformanceNavigation interface

<!-- Please describe your changes on the following line: -->
This is my first attempt. Please let me know if I should change anything.

---
<!-- Thank you for contributing to Servo! Please replace each `[ ]` by `[X]` when the step is complete, and replace `___` with appropriate data: -->
- [x] `./mach build -d` does not report any errors
- [x] `./mach test-tidy` does not report any errors
- [x] These changes fix #22828 (GitHub issue number if applicable)

<!-- Either: -->
- [ ] There are tests for these changes OR
- [x] These changes do not require tests because **not sure**

<!-- Also, please make sure that "Allow edits from maintainers" checkbox is checked, so that we can help you if you get stuck somewhere along the way.-->

<!-- Pull requests that do not address these steps are welcome, but they will require additional verification as part of the review process. -->

<!-- Reviewable:start -->
---
This change is [<img src="https://reviewable.io/review_button.svg" height="34" align="absmiddle" alt="Reviewable"/>](https://reviewable.io/reviews/servo/servo/23203)
<!-- Reviewable:end -->

components/script/dom/webidls/Performance.webidl

@@ -49,3 +49,8 @@ partial interface Performance {
 partial interface Performance {
   PerformanceNavigationTiming timing();
 };
+// https://w3c.github.io/navigation-timing/#extensions-to-the-performance-interface
+partial interface Performance {
+  [SameObject, Exposed=Window]
+  readonly attribute PerformanceNavigation navigation;
+};

components/script/dom/webidls/PerformanceNavigation.webidl

@@ -0,0 +1,18 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
+/*
+ * The origin of this IDL file is
+ * https://w3c.github.io/navigation-timing/#the-performancenavigation-interface
+ */
+
+[Exposed=Window]
+interface PerformanceNavigation {
+  const unsigned short TYPE_NAVIGATE = 0;
+  const unsigned short TYPE_RELOAD = 1;
+  const unsigned short TYPE_BACK_FORWARD = 2;
+  const unsigned short TYPE_RESERVED = 255;
+  readonly attribute unsigned short type;
+  readonly attribute unsigned short redirectCount;
+  // [Default] object toJSON();
+};