Bug 1771150 - Make fullscreen modal. r=smaug

As per https://github.com/w3c/csswg-drafts/issues/7311.

Differential Revision: https://phabricator.services.mozilla.com/D150335

dom/base/Document.cpp

@@ -14574,7 +14574,7 @@ bool Document::PopFullscreenElement(UpdateViewport aUpdateViewport) {
   }
 
   MOZ_ASSERT(removedElement->State().HasState(ElementState::FULLSCREEN));
-  removedElement->RemoveStates(ElementState::FULLSCREEN);
+  removedElement->RemoveStates(ElementState::FULLSCREEN | ElementState::MODAL);
   NotifyFullScreenChangedForMediaElement(*removedElement);
   // Reset iframe fullscreen flag.
   if (auto* iframe = HTMLIFrameElement::FromNode(removedElement)) {
@@ -14587,23 +14587,18 @@ bool Document::PopFullscreenElement(UpdateViewport aUpdateViewport) {
 }
 
 void Document::SetFullscreenElement(Element& aElement) {
-  aElement.AddStates(ElementState::FULLSCREEN);
+  ElementState statesToAdd = ElementState::FULLSCREEN;
+  if (StaticPrefs::dom_fullscreen_modal()) {
+    statesToAdd |= ElementState::MODAL;
+  }
+  aElement.AddStates(statesToAdd);
   TopLayerPush(aElement);
   NotifyFullScreenChangedForMediaElement(aElement);
   UpdateViewportScrollbarOverrideForFullscreen(this);
 }
 
-static ElementState TopLayerModalStates() {
-  ElementState modalStates = ElementState::MODAL_DIALOG;
-  if (StaticPrefs::dom_fullscreen_modal()) {
-    modalStates |= ElementState::FULLSCREEN;
-  }
-  return modalStates;
-}
-
 void Document::TopLayerPush(Element& aElement) {
-  const bool modal =
-      aElement.State().HasAtLeastOneOfStates(TopLayerModalStates());
+  const bool modal = aElement.State().HasState(ElementState::MODAL);
 
   auto predictFunc = [&aElement](Element* element) {
     return element == &aElement;
@@ -14640,7 +14635,7 @@ void Document::TopLayerPush(Element& aElement) {
 }
 
 void Document::AddModalDialog(HTMLDialogElement& aDialogElement) {
-  aDialogElement.AddStates(ElementState::MODAL_DIALOG);
+  aDialogElement.AddStates(ElementState::MODAL);
   TopLayerPush(aDialogElement);
 }
 
@@ -14650,7 +14645,7 @@ void Document::RemoveModalDialog(HTMLDialogElement& aDialogElement) {
   };
   DebugOnly<Element*> removedElement = TopLayerPop(predicate);
   MOZ_ASSERT(removedElement == &aDialogElement);
-  aDialogElement.RemoveStates(ElementState::MODAL_DIALOG);
+  aDialogElement.RemoveStates(ElementState::MODAL);
 }
 
 Element* Document::TopLayerPop(FunctionRef<bool(Element*)> aPredicate) {
@@ -14691,15 +14686,14 @@ Element* Document::TopLayerPop(FunctionRef<bool(Element*)> aPredicate) {
     return nullptr;
   }
 
-  const ElementState modalStates = TopLayerModalStates();
-  const bool modal = removedElement->State().HasAtLeastOneOfStates(modalStates);
+  const bool modal = removedElement->State().HasState(ElementState::MODAL);
 
   if (modal) {
     removedElement->RemoveStates(ElementState::TOPMOST_MODAL);
     bool foundExistingModalElement = false;
     for (const nsWeakPtr& weakPtr : Reversed(mTopLayer)) {
       nsCOMPtr<Element> element(do_QueryReferent(weakPtr));
-      if (element && element->State().HasAtLeastOneOfStates(modalStates)) {
+      if (element && element->State().HasState(ElementState::MODAL)) {
         element->AddStates(ElementState::TOPMOST_MODAL);
         foundExistingModalElement = true;
         break;

dom/base/rust/lib.rs

@@ -107,9 +107,9 @@ bitflags! {
         const AUTOFILL = 1u64 << 40;
         /// Non-standard & undocumented.
         const AUTOFILL_PREVIEW = 1u64 << 41;
-        /// State that dialog element is modal, for centered alignment
-        /// <https://html.spec.whatwg.org/multipage/#centered-alignment>
-        const MODAL_DIALOG = 1u64 << 42;
+        /// State for modal elements:
+        /// <https://drafts.csswg.org/selectors-4/#modal-state>
+        const MODAL = 1u64 << 42;
         /// <https://html.spec.whatwg.org/multipage/#inert-subtrees>
         const INERT = 1u64 << 43;
         /// State for the topmost modal element in top layer
@@ -164,7 +164,7 @@ bitflags! {
             Self::FULLSCREEN.bits |
             Self::HOVER.bits |
             Self::URLTARGET.bits |
-            Self::MODAL_DIALOG.bits |
+            Self::MODAL.bits |
             Self::INERT.bits |
             Self::TOPMOST_MODAL.bits |
             Self::REVEALED.bits;

dom/base/test/test_fullscreen_modal.html

@@ -51,6 +51,9 @@ async function testFullscreenIsModal(modal) {
 
   clickButton(/* expectEvent = */ !modal);
 
+  ok(document.fullscreenElement.matches(":fullscreen"), "Fullscreen element matches :fullscreen");
+  is(document.fullscreenElement.matches(":modal"), modal, "Fullscreen element matches :modal");
+
   await document.exitFullscreen();
   clickButton(/* expectEvent = */ true);
 }

dom/html/HTMLDialogElement.cpp

@@ -81,7 +81,7 @@ void HTMLDialogElement::Show() {
 }
 
 bool HTMLDialogElement::IsInTopLayer() const {
-  return State().HasState(ElementState::MODAL_DIALOG);
+  return State().HasState(ElementState::MODAL);
 }
 
 void HTMLDialogElement::AddToTopLayerIfNeeded() {

modules/libpref/init/StaticPrefList.yaml

@@ -2384,7 +2384,7 @@
 # This matches other browsers but historically not Gecko.
 - name: dom.fullscreen.modal
   type: bool
-  value: false
+  value: true
   mirror: always
 
 # Whether the Gamepad API is enabled

servo/components/style/gecko/non_ts_pseudo_class_list.rs

@@ -53,7 +53,7 @@ macro_rules! apply_non_ts_list {
                 ("-moz-devtools-highlighted", MozDevtoolsHighlighted, DEVTOOLS_HIGHLIGHTED, PSEUDO_CLASS_ENABLED_IN_UA_SHEETS),
                 ("-moz-styleeditor-transitioning", MozStyleeditorTransitioning, STYLEEDITOR_TRANSITIONING, PSEUDO_CLASS_ENABLED_IN_UA_SHEETS),
                 ("fullscreen", Fullscreen, FULLSCREEN, _),
-                ("modal", Modal, MODAL_DIALOG, _),
+                ("modal", Modal, MODAL, _),
                 ("-moz-topmost-modal", MozTopmostModal, TOPMOST_MODAL, PSEUDO_CLASS_ENABLED_IN_UA_SHEETS),
                 ("-moz-broken", MozBroken, BROKEN, _),
                 ("-moz-loading", MozLoading, LOADING, _),