Fix incorrect documentation and add track_caller to DomRefCell methods (servo#33111)

* Fix DomRefCell documentation about panic behaviour

Fixes servo#33099

Signed-off-by: Simon Wülker <[email protected]>

* Annotate DomRefCell::borrow/borrow_mut with #[track_caller]

Fixes servo#27336

Signed-off-by: Simon Wülker <[email protected]>

---------

Signed-off-by: Simon Wülker <[email protected]>

Author: simonwuelker

components/script/dom/bindings/cell.rs

@@ -35,6 +35,12 @@ impl<T> DomRefCell<T> {
     /// Unlike RefCell::borrow, this method is unsafe because it does not return a Ref, thus leaving
     /// the borrow flag untouched. Mutably borrowing the RefCell while the reference returned by
     /// this method is alive is undefined behaviour.
+    ///
+    /// # Panics
+    ///
+    /// Panics if this is called from anywhere other than the layout thread
+    ///
+    /// Panics if the value is currently mutably borrowed.
     #[allow(unsafe_code)]
     pub unsafe fn borrow_for_layout(&self) -> &T {
         assert_in_layout();
@@ -50,6 +56,10 @@ impl<T> DomRefCell<T> {
     /// Unlike RefCell::borrow, this method is unsafe because it does not return a Ref, thus leaving
     /// the borrow flag untouched. Mutably borrowing the RefCell while the reference returned by
     /// this method is alive is undefined behaviour.
+    ///
+    /// # Panics
+    ///
+    /// Panics if this is called from anywhere other than the script thread.
     #[allow(unsafe_code, clippy::mut_from_ref)]
     pub unsafe fn borrow_for_script_deallocation(&self) -> &mut T {
         assert_in_script();
@@ -64,6 +74,10 @@ impl<T> DomRefCell<T> {
     /// Unlike RefCell::borrow, this method is unsafe because it does not return a Ref, thus leaving
     /// the borrow flag untouched. Mutably borrowing the RefCell while the reference returned by
     /// this method is alive is undefined behaviour.
+    ///
+    /// # Panics
+    ///
+    /// Panics if this is called from anywhere other than the layout thread.
     #[allow(unsafe_code, clippy::mut_from_ref)]
     pub unsafe fn borrow_mut_for_layout(&self) -> &mut T {
         assert_in_layout();
@@ -88,9 +102,8 @@ impl<T> DomRefCell<T> {
     ///
     /// # Panics
     ///
-    /// Panics if this is called off the script thread.
-    ///
     /// Panics if the value is currently mutably borrowed.
+    #[track_caller]
     pub fn borrow(&self) -> Ref<T> {
         self.value.borrow()
     }
@@ -102,9 +115,8 @@ impl<T> DomRefCell<T> {
     ///
     /// # Panics
     ///
-    /// Panics if this is called off the script thread.
-    ///
     /// Panics if the value is currently borrowed.
+    #[track_caller]
     pub fn borrow_mut(&self) -> RefMut<T> {
         self.value.borrow_mut()
     }