script: Fully implement DocumentOrShadowRoot#activeElement (#43861)

`DocumentOrShadowRoot#activeElement` should return retargeted results.
What that means is that if the DOM anchor of the `Document`'s focused
focusable area is within a shadow root, `Document#activeElement` should
return the shadow host. This change implements that behavior, properly
returning the `activeElement` from both `Document` and `ShadowRoot`.

Testing: This causes a decent number of WPT tests and subtests to start
passing. One subtest starts to fail, because it uses the `autofocus`
attribute
which we do not yet support.

Signed-off-by: Martin Robinson <mrobinson@igalia.com>

components/script/dom/document/document.rs

@@ -371,7 +371,7 @@ pub(crate) struct Document {
     /// Whether the DOMContentLoaded event has already been dispatched.
     domcontentloaded_dispatched: Cell<bool>,
     /// The element that currently has the document focus context.
-    focused: MutNullableDom<Element>,
+    focused_element: MutNullableDom<Element>,
     /// The last sequence number sent to the constellation.
     #[no_trace]
     focus_sequence: Cell<FocusSequenceNumber>,
@@ -1336,8 +1336,8 @@ impl Document {
 
     /// Return the element that currently has focus.
     // https://w3c.github.io/uievents/#events-focusevent-doc-focus
-    pub(crate) fn get_focused_element(&self) -> Option<DomRoot<Element>> {
-        self.focused.get()
+    pub(crate) fn focused_element(&self) -> Option<DomRoot<Element>> {
+        self.focused_element.get()
     }
 
     /// Get the last sequence number sent to the constellation.
@@ -1368,7 +1368,7 @@ impl Document {
     /// TODO: Handle the "focus changed during ongoing navigation" flag.
     pub(crate) fn perform_focus_fixup_rule(&self, can_gc: CanGc) {
         if self
-            .focused
+            .focused_element
             .get()
             .as_deref()
             .is_none_or(|focused| focused.is_focusable_area())
@@ -1409,9 +1409,10 @@ impl Document {
                 },
                 true,
             ),
-            FocusOperation::Unfocus => {
-                (self.focused.get().as_deref().map(DomRoot::from_ref), false)
-            },
+            FocusOperation::Unfocus => (
+                self.focused_element.get().as_deref().map(DomRoot::from_ref),
+                false,
+            ),
         };
 
         if !new_focus_state {
@@ -1426,7 +1427,7 @@ impl Document {
             }
         }
 
-        let old_focused = self.focused.get();
+        let old_focused = self.focused_element.get();
         let old_focus_state = self.has_focus.get();
 
         debug!(
@@ -1470,7 +1471,7 @@ impl Document {
             self.fire_focus_event(FocusEventType::Blur, self.global().upcast(), None, can_gc);
         }
 
-        self.focused.set(new_focused.as_deref());
+        self.focused_element.set(new_focused.as_deref());
         self.has_focus.set(new_focus_state);
 
         if old_focus_state != new_focus_state && new_focus_state {
@@ -3855,7 +3856,7 @@ impl Document {
             ready_state: Cell::new(ready_state),
             domcontentloaded_dispatched: Cell::new(domcontentloaded_dispatched),
 
-            focused: Default::default(),
+            focused_element: Default::default(),
             focus_sequence: Cell::new(FocusSequenceNumber::default()),
             has_focus: Cell::new(has_focus),
             current_script: Default::default(),
@@ -5051,11 +5052,7 @@ impl DocumentMethods<crate::DomTypeHolder> for Document {
 
     /// <https://html.spec.whatwg.org/multipage/#dom-document-activeelement>
     fn GetActiveElement(&self) -> Option<DomRoot<Element>> {
-        self.document_or_shadow_root.get_active_element(
-            self.get_focused_element(),
-            self.GetBody(),
-            self.GetDocumentElement(),
-        )
+        self.document_or_shadow_root.active_element(self.upcast())
     }
 
     /// <https://html.spec.whatwg.org/multipage/#dom-document-hasfocus>

components/script/dom/document/document_event_handler.rs

@@ -1357,7 +1357,7 @@ impl DocumentEventHandler {
         can_gc: CanGc,
     ) -> InputEventResult {
         let document = self.window.Document();
-        let focused = document.get_focused_element();
+        let focused = document.focused_element();
         let body = document.GetBody();
 
         let target = match (&focused, &body) {
@@ -1434,7 +1434,7 @@ impl DocumentEventHandler {
         // spec: https://w3c.github.io/uievents/#compositionupdate
         // spec: https://w3c.github.io/uievents/#compositionend
         // > Event.target : focused element processing the composition
-        let focused = document.get_focused_element();
+        let focused = document.focused_element();
         let target = if let Some(elem) = &focused {
             elem.upcast()
         } else {
@@ -1752,7 +1752,7 @@ impl DocumentEventHandler {
 
         // Step 6 if the context is editable:
         let document = self.window.Document();
-        let target = target.or(document.get_focused_element());
+        let target = target.or(document.focused_element());
         let target = target
             .map(|target| DomRoot::from_ref(target.upcast()))
             .or_else(|| {
@@ -2018,7 +2018,7 @@ impl DocumentEventHandler {
         let mut starting_point = self
             .window
             .Document()
-            .get_focused_element()
+            .focused_element()
             .map(DomRoot::upcast::<Node>);
 
         // > 2. If there is a sequential focus navigation starting point defined and it is inside
@@ -2242,7 +2242,7 @@ impl DocumentEventHandler {
 
         let document = self.window.Document();
         let mut scrolling_box = document
-            .get_focused_element()
+            .focused_element()
             .or(self.most_recently_clicked_element.get())
             .and_then(|element| element.scrolling_box(ScrollContainerQueryFlags::Inclusive))
             .unwrap_or_else(|| {

components/script/dom/document/documentorshadowroot.rs

@@ -10,6 +10,8 @@ use embedder_traits::UntrustedNodeAddress;
 use js::rust::HandleValue;
 use layout_api::ElementsFromPointFlags;
 use rustc_hash::FxBuildHasher;
+use script_bindings::codegen::GenericBindings::DocumentBinding::DocumentMethods;
+use script_bindings::codegen::GenericBindings::WindowBinding::WindowMethods;
 use script_bindings::error::{Error, ErrorResult};
 use script_bindings::script_runtime::{CanGc, JSContext};
 use servo_arc::Arc;
@@ -21,7 +23,9 @@ use style::stylesheets::{Stylesheet, StylesheetContents};
 use stylo_atoms::Atom;
 use webrender_api::units::LayoutPoint;
 
+use crate::dom::Document;
 use crate::dom::bindings::cell::DomRefCell;
+use crate::dom::bindings::codegen::Bindings::NodeBinding::GetRootNodeOptions;
 use crate::dom::bindings::codegen::Bindings::NodeBinding::Node_Binding::NodeMethods;
 use crate::dom::bindings::codegen::Bindings::ShadowRootBinding::ShadowRootMethods;
 use crate::dom::bindings::conversions::{ConversionResult, SafeFromJSValConvertible};
@@ -31,10 +35,9 @@ use crate::dom::bindings::root::{Dom, DomRoot};
 use crate::dom::bindings::trace::HashMapTracedValues;
 use crate::dom::css::stylesheetlist::StyleSheetListOwner;
 use crate::dom::element::Element;
-use crate::dom::html::htmlelement::HTMLElement;
 use crate::dom::node::{self, Node, VecPreOrderInsertionHelper};
 use crate::dom::shadowroot::ShadowRoot;
-use crate::dom::types::CSSStyleSheet;
+use crate::dom::types::{CSSStyleSheet, EventTarget};
 use crate::dom::window::Window;
 use crate::stylesheet_set::StylesheetSetRef;
 
@@ -221,23 +224,48 @@ impl DocumentOrShadowRoot {
         elements
     }
 
-    // https://html.spec.whatwg.org/multipage/#dom-document-activeelement
-    pub(crate) fn get_active_element(
-        &self,
-        focused_element: Option<DomRoot<Element>>,
-        body: Option<DomRoot<HTMLElement>>,
-        document_element: Option<DomRoot<Element>>,
-    ) -> Option<DomRoot<Element>> {
-        // TODO: Step 2.
+    /// <https://html.spec.whatwg.org/multipage/#dom-documentorshadowroot-activeelement-dev>
+    pub(crate) fn active_element(&self, this: &Node) -> Option<DomRoot<Element>> {
+        // Step 1. Let candidate be this's node document's focused area's DOM anchor.
+        //
+        // Note: When `Document::focused_element` returns `None`, that means that the
+        // `Document` / viewport itself is focused.
+        let document = self.window.Document();
+        let candidate = match document.focused_element() {
+            Some(candidate) => DomRoot::upcast::<Node>(candidate),
+            None => DomRoot::upcast::<Node>(document.clone()),
+        };
 
-        match focused_element {
-            Some(element) => Some(element), // Step 3. and 4.
-            None => match body {
-                // Step 5.
-                Some(body) => Some(DomRoot::upcast(body)),
-                None => document_element,
-            },
+        // Step 2. Set candidate to the result of retargeting candidate against this.
+        //
+        // Note: `retarget()` operates on `EventTarget`, but we can be assured that we are
+        // only dealing with various kinds of `Node`s here.
+        let candidate =
+            DomRoot::downcast::<Node>(candidate.upcast::<EventTarget>().retarget(this.upcast()))?;
+
+        // Step 3. If candidate's root is not this, then return null.
+        if this != &*candidate.GetRootNode(&GetRootNodeOptions::empty()) {
+            return None;
         }
+
+        // Step 4. If candidate is not a Document object, then return candidate.
+        if let Some(candidate) = DomRoot::downcast::<Element>(candidate.clone()) {
+            return Some(candidate);
+        }
+        assert!(candidate.is::<Document>());
+
+        // Step 5. If candidate has a body element, then return that body element.
+        if let Some(body) = document.GetBody() {
+            return Some(DomRoot::upcast(body));
+        }
+
+        // Step 6. If candidate's document element is non-null, then return that document element.
+        if let Some(document_element) = document.GetDocumentElement() {
+            return Some(document_element);
+        }
+
+        // Step 7. Return null.
+        None
     }
 
     /// Remove a stylesheet owned by `owner` from the list of document sheets.

components/script/dom/html/htmlelement.rs

@@ -1339,7 +1339,7 @@ impl VirtualMethods for HTMLElement {
         // TODO: Should this also happen for non-HTML elements such as SVG elements?
         let element = self.as_element();
         if document
-            .get_focused_element()
+            .focused_element()
             .is_some_and(|focused_element| &*focused_element == element)
         {
             document.focus(

components/script/dom/node/focus.rs

@@ -95,7 +95,7 @@ impl Node {
             .and_then(Element::shadow_root)
             .is_some_and(|shadow_root| shadow_root.DelegatesFocus())
         {
-            if let Some(focused_element) = self.owner_document().get_focused_element() {
+            if let Some(focused_element) = self.owner_document().focused_element() {
                 // >   Step 2. If focus target is a shadow-including inclusive ancestor of
                 // >           focusedElement, then return focusedElement.
                 if self

components/script/dom/shadowroot.rs

@@ -179,11 +179,6 @@ impl ShadowRoot {
         &self.document
     }
 
-    pub(crate) fn get_focused_element(&self) -> Option<DomRoot<Element>> {
-        // XXX get retargeted focused element
-        None
-    }
-
     pub(crate) fn stylesheet_count(&self) -> usize {
         self.author_styles.borrow().stylesheets.len()
     }
@@ -387,8 +382,7 @@ impl ShadowRoot {
 impl ShadowRootMethods<crate::DomTypeHolder> for ShadowRoot {
     /// <https://html.spec.whatwg.org/multipage/#dom-document-activeelement>
     fn GetActiveElement(&self) -> Option<DomRoot<Element>> {
-        self.document_or_shadow_root
-            .get_active_element(self.get_focused_element(), None, None)
+        self.document_or_shadow_root.active_element(self.upcast())
     }
 
     /// <https://drafts.csswg.org/cssom-view/#dom-document-elementfrompoint>

tests/wpt/meta/html/interaction/focus/focusgroup/tentative/sequential-navigation/arrow-key-handler-multi-tab-stop.html.ini

@@ -5,8 +5,5 @@
   [Shift+Tab escape from video element inside focusgroup goes to adjacent item]
     expected: FAIL
 
-  [Tab through video controls outside focusgroup follows normal tab order]
-    expected: FAIL
-
   [Tab escape from inside video shadow DOM controls reaches adjacent focusgroup item]
     expected: FAIL

tests/wpt/meta/html/interaction/focus/the-autofocus-attribute/autofocus-in-not-fully-active-document.html.ini

@@ -0,0 +1,3 @@
+[autofocus-in-not-fully-active-document.html]
+  [Autofocus element in not-fully-active document should not be queued.]
+    expected: FAIL

tests/wpt/meta/html/rendering/non-replaced-elements/flow-content-0/slot-element-focusable.tentative.html.ini

@@ -1,6 +0,0 @@
-[slot-element-focusable.tentative.html]
-  [slot element with display: block should be focusable]
-    expected: FAIL
-
-  [slot element with default style should be focusable]
-    expected: FAIL

tests/wpt/meta/html/rendering/non-replaced-elements/flow-content-0/slot-element-tabbable.tentative.html.ini

@@ -1,6 +0,0 @@
-[slot-element-tabbable.tentative.html]
-  [slot element with display: block should be focusable]
-    expected: FAIL
-
-  [slot element with default style should be focusable]
-    expected: FAIL

tests/wpt/meta/html/semantics/interactive-elements/the-dialog-element/dialog-focus-previous-outside.html.ini

@@ -1,7 +1,4 @@
 [dialog-focus-previous-outside.html]
-  [Focus restore should not occur when the focused element is in a shadowroot outside of the dialog.]
-    expected: FAIL
-
   [Focus restore should occur when the focused element is in a shadowroot inside the dialog.]
     expected: FAIL
 

tests/wpt/meta/html/semantics/interactive-elements/the-dialog-element/focus-after-close.html.ini

@@ -7,6 +7,3 @@
 
   [Focus should be moved to the previously focused element even if it has moved to shadow DOM root in between show/close]
     expected: FAIL
-
-  [Focus should be moved to the shadow DOM host if the previouly focused element is a shadow DOM node]
-    expected: FAIL

tests/wpt/meta/shadow-dom/ShadowRoot-interface.html.ini

@@ -1,6 +0,0 @@
-[ShadowRoot-interface.html]
-  [ShadowRoot.activeElement must return the focused element of the context object when shadow root is open.]
-    expected: FAIL
-
-  [ShadowRoot.activeElement must return the focused element of the context object when shadow root is closed.]
-    expected: FAIL

tests/wpt/meta/shadow-dom/focus-navigation/focus-navigation-web-component-radio.html.ini

@@ -1,3 +0,0 @@
-[focus-navigation-web-component-radio.html]
-  [Focus for web component input type elements should be bound by <form> inside shadow DOM]
-    expected: FAIL

tests/wpt/meta/shadow-dom/focus-within-shadow.html.ini

@@ -1,3 +0,0 @@
-[focus-within-shadow.html]
-  [Don't clear focus within shadow root if light DOM children are cleared]
-    expected: FAIL

tests/wpt/meta/shadow-dom/focus/DocumentOrShadowRoot-activeElement.html.ini

@@ -1,12 +0,0 @@
-[DocumentOrShadowRoot-activeElement.html]
-  [activeElement on document & shadow root when focused element is in the shadow tree]
-    expected: FAIL
-
-  [activeElement on a neighboring host when focused element is in another shadow tree]
-    expected: FAIL
-
-  [activeElement when focused element is in a nested shadow tree]
-    expected: FAIL
-
-  [activeElement when focused element is in a parent shadow tree]
-    expected: FAIL

tests/wpt/meta/shadow-dom/focus/delegatesFocus-tabindex-change.html.ini

@@ -1,3 +0,0 @@
-[delegatesFocus-tabindex-change.html]
-  [Setting tabindex on the shadow host of a focused element with delegatesFocus should not change focus.]
-    expected: FAIL

tests/wpt/meta/shadow-dom/focus/focus-autofocus.html.ini

@@ -5,8 +5,5 @@
   [Focus should be delegated to the autofocus element when the inner host has delegates focus]
     expected: FAIL
 
-  [Focus should not be delegated to the slotted elements]
-    expected: FAIL
-
   [Focus should be delegated to the nested div which has autofocus based on the tree order]
     expected: FAIL

tests/wpt/meta/shadow-dom/focus/focus-method-delegatesFocus.html.ini

@@ -1,39 +0,0 @@
-[focus-method-delegatesFocus.html]
-  [focus() on host with delegatesFocus, all tabindex=0]
-    expected: FAIL
-
-  [focus() on host with delegatesFocus & tabindex =-1, all other tabindex=0]
-    expected: FAIL
-
-  [focus() on host with delegatesFocus & no tabindex, all other tabindex=0]
-    expected: FAIL
-
-  [focus() on host with delegatesFocus & tabindex = 0, all other tabindex=-1]
-    expected: FAIL
-
-  [focus() on host with delegatesFocus, all tabindex=-1]
-    expected: FAIL
-
-  [focus() on host with delegatesFocus & tabindex=0, #belowSlots with tabindex=0]
-    expected: FAIL
-
-  [focus() on host with delegatesFocus & tabindex=0, #aboveSlots and #belowSlots with tabindex=0]
-    expected: FAIL
-
-  [focus() on host with delegatesFocus & tabindex=0, #aboveSlots with tabindex=0 and #belowSlots with tabindex=1]
-    expected: FAIL
-
-  [focus() on host with delegatesFocus & tabindex=0, #slottedToFirstSlot, #slottedToSecondSlot, #belowSlots  with tabindex=0]
-    expected: FAIL
-
-  [focus() on host with delegatesFocus and already-focused non-first shadow descendant]
-    expected: FAIL
-
-  [focus() on host with delegatesFocus with another host with no delegatesFocus and a focusable child]
-    expected: FAIL
-
-  [focus() on host with delegatesFocus with another host with delegatesFocus and a focusable child]
-    expected: FAIL
-
-  [focus() on host with delegatesFocus and slotted focusable children]
-    expected: FAIL

tests/wpt/meta/shadow-dom/focus/focus-method-with-delegatesFocus.html.ini

@@ -1,9 +0,0 @@
-[focus-method-with-delegatesFocus.html]
-  [on focus(), focusable xshadow2 with delegatesFocus=true delegates focus into its inner element.]
-    expected: FAIL
-
-  [if an element within shadow is focused, focusing on shadow host should not slide focus to its inner element.]
-    expected: FAIL
-
-  [xshadow2.focus() shouldn't move focus to #one when its inner element is already focused.]
-    expected: FAIL

tests/wpt/meta/shadow-dom/focus/focus-slot-box-generated-tabindex-0.html.ini

@@ -1,3 +0,0 @@
-[focus-slot-box-generated-tabindex-0.html]
-  [slot with tabindex=0 that generates a box should be focusable]
-    expected: FAIL

tests/wpt/meta/shadow-dom/focus/focus-tabindex-order-shadow-varying-tabindex-2.html.ini

@@ -1,3 +0,0 @@
-[focus-tabindex-order-shadow-varying-tabindex-2.html]
-  [Order with different tabindex on host]
-    expected: FAIL

tests/wpt/meta/shadow-dom/focus/focus-tabindex-order-shadow-varying-tabindex-3.html.ini

@@ -1,3 +0,0 @@
-[focus-tabindex-order-shadow-varying-tabindex-3.html]
-  [Order with different tabindex on host]
-    expected: FAIL

tests/wpt/meta/shadow-dom/untriaged/elements-and-dom-objects/shadowroot-object/shadowroot-attributes/test-007.html.ini

@@ -1,3 +0,0 @@
-[test-007.html]
-  [A_10_01_01_03_01_T01]
-    expected: FAIL

tests/wpt/meta/shadow-dom/untriaged/user-interaction/active-element/test-001.html.ini

@@ -1,3 +0,0 @@
-[test-001.html]
-  [A_07_03_01_T01]
-    expected: FAIL

tests/wpt/meta/shadow-dom/untriaged/user-interaction/active-element/test-002.html.ini

@@ -1,3 +0,0 @@
-[test-002.html]
-  [A_07_03_02_T01]
-    expected: FAIL

tests/wpt/meta/visual-viewport/viewport-apply-initial-scale-after-navigation.html.ini

@@ -1,2 +0,0 @@
-[viewport-apply-initial-scale-after-navigation.html]
-  expected: TIMEOUT