From 218ad8f574317846b591784c4c60af07aa72730d Mon Sep 17 00:00:00 2001
From: Martin Robinson <mrobinson@igalia.com>
Date: Fri, 18 Aug 2023 06:00:44 +0200
Subject: [PATCH] Fix /custom-elements/when-defined-reentry-crash.html (#30121)

The problem is a double-borrow of the `when_defined` member. The fix is
to let go of the borrow before resolving the promise which will
eventually try to borrow `when_defined` again.

Fixes #30120.
---
 components/script/dom/customelementregistry.rs | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/components/script/dom/customelementregistry.rs b/components/script/dom/customelementregistry.rs
index df458ec90c3..ba36a2d30df 100644
--- a/components/script/dom/customelementregistry.rs
+++ b/components/script/dom/customelementregistry.rs
@@ -397,7 +397,8 @@ impl CustomElementRegistryMethods for CustomElementRegistry {
         }
 
         // Step 16, 16.3
-        if let Some(promise) = self.when_defined.borrow_mut().remove(&name) {
+        let promise = self.when_defined.borrow_mut().remove(&name);
+        if let Some(promise) = promise {
             unsafe {
                 rooted!(in(*cx) let mut constructor = UndefinedValue());
                 definition