Auto merge of #13100 - nox:better-getters, r=Ms2ger

Use Option<T> to return from getters

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components/script/dom/document.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 http://mozilla.org/MPL/2.0/. */
 
+use core::nonzero::NonZero;
 use document_loader::{DocumentLoader, LoadType};
 use dom::activation::{ActivationSource, synthetic_click_activation};
 use dom::attr::Attr;
@@ -116,7 +117,6 @@ use std::collections::hash_map::Entry::{Occupied, Vacant};
 use std::default::Default;
 use std::iter::once;
 use std::mem;
-use std::ptr;
 use std::rc::Rc;
 use std::sync::Arc;
 use string_cache::{Atom, QualName};
@@ -2710,8 +2710,9 @@ impl DocumentMethods for Document {
         self.set_body_attribute(&atom!("text"), value)
     }
 
+    #[allow(unsafe_code)]
     // https://html.spec.whatwg.org/multipage/#dom-tree-accessors:dom-document-nameditem-filter
-    fn NamedGetter(&self, _cx: *mut JSContext, name: DOMString, found: &mut bool) -> *mut JSObject {
+    fn NamedGetter(&self, _cx: *mut JSContext, name: DOMString) -> Option<NonZero<*mut JSObject>> {
         #[derive(JSTraceable, HeapSizeOf)]
         struct NamedElementFilter {
             name: Atom,
@@ -2777,23 +2778,24 @@ impl DocumentMethods for Document {
                                    .peekable();
             if let Some(first) = elements.next() {
                 if elements.peek().is_none() {
-                    *found = true;
                     // TODO: Step 2.
                     // Step 3.
-                    return first.reflector().get_jsobject().get();
+                    return unsafe {
+                        Some(NonZero::new(first.reflector().get_jsobject().get()))
+                    };
                 }
             } else {
-                *found = false;
-                return ptr::null_mut();
+                return None;
             }
         }
         // Step 4.
-        *found = true;
         let filter = NamedElementFilter {
             name: name,
         };
         let collection = HTMLCollection::create(self.window(), root, box filter);
-        collection.reflector().get_jsobject().get()
+        unsafe {
+            Some(NonZero::new(collection.reflector().get_jsobject().get()))
+        }
     }
 
     // https://html.spec.whatwg.org/multipage/#dom-tree-accessors:supported-property-names