Replace NonZero<*mut JSObject> with a wrapper to enable local trait impls.

components/script/dom/bindings/nonnull.rs

@@ -0,0 +1,24 @@
+/* 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 http://mozilla.org/MPL/2.0/. */
+
+//! A wrapper type for `NonZero<*mut JSObject>`, to enable local trait impls
+
+use js::jsapi::JSObject;
+use nonzero::NonZero;
+
+/// A wrapper type for `NonZero<*mut JSObject>`, to enable local trait impls
+#[derive(Clone, Copy)]
+pub struct NonNullJSObjectPtr(NonZero<*mut JSObject>);
+
+impl NonNullJSObjectPtr {
+    #[inline]
+    pub unsafe fn new_unchecked(ptr: *mut JSObject) -> Self {
+        NonNullJSObjectPtr(NonZero::new_unchecked(ptr))
+    }
+
+    #[inline]
+    pub fn get(self) -> *mut JSObject {
+        self.0.get()
+    }
+}