Auto merge of #25914 - paulrouget:lessRAF, r=jdm

Stop embedder calls and fake rAF when window not visible

This addresses 2 issues:

- a rAF loop might still be ongoing when the window is invisible if script decided that the rAF were going too fast (spurious rAF)
- a hidden window does not run the rAF loop, but the embedder would still be in animating mode

---
<!-- 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
- [ ] These changes fix #___ (GitHub issue number if applicable)

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

<!-- 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. -->

0 files changed, 0 insertions, 0 deletions