Auto merge of #23253 - BartGitHub:refactor-promise-compartment, r=jdm

Refactor promise compartment

<!-- Please describe your changes on the following line: -->
This PR adds a mechanism to verify that certain code is executed inside a ```JSAutoCompartment```, and applies this to the ```Promise::new_in_current_compartment``` constructor.

r? @jdm

---
<!-- 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 #23167

<!-- Either: -->
- [x] These changes do not require tests because they do not change existing functionality.

<!-- 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/23253)
<!-- Reviewable:end -->

1 files changed, 6 insertions, 2 deletions

diff --git a/components/script/dom/htmlmediaelement.rs b/components/script/dom/htmlmediaelement.rs
index 066c53484e6..c6b9c8a7939 100644
--- a/components/script/dom/htmlmediaelement.rs
+++ b/components/script/dom/htmlmediaelement.rs
@@ -2,6 +2,7 @@
  * 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/. */
 
+use crate::compartments::{AlreadyInCompartment, InCompartment};
 use crate::document_loader::{LoadBlocker, LoadType};
 use crate::dom::attr::Attr;
 use crate::dom::audiotrack::AudioTrack;
@@ -1683,9 +1684,12 @@ impl HTMLMediaElementMethods for HTMLMediaElement {
     }
 
     // https://html.spec.whatwg.org/multipage/#dom-media-play
-    #[allow(unsafe_code)]
     fn Play(&self) -> Rc<Promise> {
-        let promise = unsafe { Promise::new_in_current_compartment(&self.global()) };
+        let in_compartment_proof = AlreadyInCompartment::assert(&self.global());
+        let promise = Promise::new_in_current_compartment(
+            &self.global(),
+            InCompartment::Already(&in_compartment_proof),
+        );
         // Step 1.
         // FIXME(nox): Reject promise if not allowed to play.