[Site Isolation] Fix some cases where we unnecessarily skip code on o…

…ut-of-process frames

https://bugs.webkit.org/show_bug.cgi?id=265563
rdar://118970867

Reviewed by Alex Christensen.

There are several places where we are unnecessarily skipping code on out-of-process frames. We should
avoid downcasting to a local frame if it's not required.

* Source/WebCore/bindings/js/JSLocalDOMWindowCustom.cpp:
(WebCore::jsLocalDOMWindowGetOwnPropertySlotRestrictedAccess):
* Source/WebCore/css/query/MediaQueryFeatures.cpp:
(WebCore::MQ::Features::color):
(WebCore::MQ::Features::dynamicRange):
* Source/WebCore/dom/TreeScope.cpp:
(WebCore::focusedFrameOwnerElement):
* Source/WebCore/html/HTMLFrameElementBase.cpp:
(WebCore::HTMLFrameElementBase::didAttachRenderers):
* Source/WebCore/html/MediaElementSession.cpp:
(WebCore::isElementRectMostlyInMainFrame):
* Source/WebCore/inspector/InspectorFrontendClientLocal.cpp:
(WebCore::InspectorFrontendClientLocal::canAttachWindow):
(WebCore::InspectorFrontendClientLocal::changeAttachedWindowHeight):

(WebCore::InspectorFrontendClientLocal::changeAttachedWindowWidth):

There is also a behavior change in this function. Previously, we did a null check on `otherMainFrame` and
then used the width on `localMainFrame`, which seemed like a bug.

(WebCore::InspectorFrontendClientLocal::restoreAttachedWindowHeight):
* Source/WebCore/inspector/InspectorFrontendHost.cpp:
(WebCore::InspectorFrontendHost::copyText):
* Source/WebCore/inspector/InspectorOverlay.cpp:
(WebCore::localPointToRootPoint):
(WebCore::contentsQuadToCoordinateSystem):
(WebCore::buildRendererHighlight):
(WebCore::drawShapeHighlight):
(WebCore::InspectorOverlay::paint):
(WebCore::InspectorOverlay::highlightQuad):
(WebCore::InspectorOverlay::update):
(WebCore::InspectorOverlay::showPaintRect):
(WebCore::InspectorOverlay::buildGridOverlay):
* Source/WebCore/inspector/agents/InspectorPageAgent.cpp:
(WebCore::InspectorPageAgent::didPaint):
* Source/WebCore/loader/FrameLoader.cpp:
(WebCore::FrameLoader::completed):
* Source/WebCore/page/DragController.cpp:
(WebCore::DragController::beginDrag):
* Source/WebCore/page/FocusController.cpp:
(WebCore::FocusController::setFocusedInternal):
(WebCore::FocusController::advanceFocusInDocumentOrder):
(WebCore::FocusController::setIsVisibleAndActiveInternal):
* Source/WebCore/page/IntersectionObserver.cpp:
(WebCore::IntersectionObserver::computeIntersectionState const):
* Source/WebCore/page/LocalDOMWindow.cpp:
(WebCore::LocalDOMWindow::adjustWindowRect):
(WebCore::LocalDOMWindow::moveTo const):
* Source/WebCore/page/LocalFrameView.cpp:
(WebCore::LocalFrameView::shouldUpdateCompositingLayersAfterScrolling const):
* Source/WebCore/page/Page.cpp:
(WebCore::Page::findString):
(WebCore::Page::screenPropertiesDidChange):
(WebCore::Page::lockAllOverlayScrollbarsToHidden):
(WebCore::Page::setVerticalScrollElasticity):
(WebCore::Page::setDebugger):
(WebCore::Page::subframeCount const):
* Source/WebCore/page/PageOverlay.cpp:
(WebCore::PageOverlay::bounds const):
(WebCore::PageOverlay::drawRect):
* Source/WebCore/page/ResourceUsageOverlay.cpp:
(WebCore::ResourceUsageOverlay::~ResourceUsageOverlay):
(WebCore::ResourceUsageOverlay::mouseEvent):
* Source/WebCore/page/SpatialNavigation.cpp:
(WebCore::rectToAbsoluteCoordinates):
* Source/WebCore/page/mac/DragControllerMac.mm:
(WebCore::DragController::cleanupAfterSystemDrag):
* Source/WebCore/page/mac/ImageOverlayControllerMac.mm:
(WebCore::ImageOverlayController::updateDataDetectorHighlights):
(WebCore::ImageOverlayController::platformHandleMouseEvent):
* Source/WebCore/page/mac/ServicesOverlayController.mm:
(WebCore::ServicesOverlayController::buildSelectionHighlight):
(WebCore::ServicesOverlayController::mouseEvent):
(WebCore::ServicesOverlayController::handleClick):
* Source/WebCore/page/scrolling/AsyncScrollingCoordinator.cpp:
(WebCore::AsyncScrollingCoordinator::setFrameScrollingNodeState):
* Source/WebCore/page/scrolling/ScrollingCoordinator.cpp:
(WebCore::ScrollingCoordinator::shouldUpdateScrollLayerPositionSynchronously const):
* Source/WebKit/WebProcess/FullScreen/WebFullScreenManager.cpp:
(WebKit::WebFullScreenManager::saveScrollPosition):
* Source/WebKit/WebProcess/InjectedBundle/DOM/InjectedBundleNodeHandle.cpp:
(WebKit::InjectedBundleNodeHandle::htmlIFrameElementContentFrame):
* Source/WebKit/WebProcess/Network/WebLoaderStrategy.cpp:
(WebKit::addParametersShared):
* Source/WebKit/WebProcess/WebCoreSupport/ShareableBitmapUtilities.cpp:
(WebKit::createShareableBitmap):
* Source/WebKit/WebProcess/WebPage/FindController.cpp:
(WebKit::FindController::rectsForTextMatchesInRect):
* Source/WebKit/WebProcess/WebPage/WebFrame.cpp:
(WebKit::WebFrame::size const):
(WebKit::WebFrame::jsContextForServiceWorkerWorld):
(WebKit::WebFrame::contentBounds const):
(WebKit::WebFrame::visibleContentBounds const):
(WebKit::WebFrame::scrollOffset const):
(WebKit::WebFrame::hasVerticalScrollbar const):
* Source/WebKit/WebProcess/WebPage/WebPage.cpp:
(WebKit::WebPage::clearMainFrameName):
(WebKit::WebPage::setSize):
(WebKit::WebPage::scaleView):
(WebKit::snapshotColorSpace):

Canonical link: https://commits.webkit.org/271358@main

Source/WebCore/bindings/js/JSLocalDOMWindowCustom.cpp

@@ -156,9 +156,8 @@ bool jsLocalDOMWindowGetOwnPropertySlotRestrictedAccess(JSDOMGlobalObject* thisO
     // properties that are in Moz but not IE. Since we have some of these, we have to do it
     // the Moz way.
     // FIXME: Add support to named attributes on RemoteFrames.
-    auto* frame = window.frame();
-    if (auto* localFrame = dynamicDowncast<LocalFrame>(frame)) {
-        if (auto* scopedChild = dynamicDowncast<LocalFrame>(localFrame->tree().scopedChildBySpecifiedName(propertyNameToAtomString(propertyName)))) {
+    if (RefPtr frame = window.frame()) {
+        if (auto* scopedChild = dynamicDowncast<LocalFrame>(frame->tree().scopedChildBySpecifiedName(propertyNameToAtomString(propertyName)))) {
             slot.setValue(thisObject, PropertyAttribute::ReadOnly | PropertyAttribute::DontEnum, toJS(&lexicalGlobalObject, scopedChild->document()->domWindow()));
             return true;
         }

Source/WebCore/css/query/MediaQueryFeatures.cpp

@@ -250,9 +250,7 @@ const FeatureSchema& color()
     static MainThreadNeverDestroyed<IntegerSchema> schema {
         "color"_s,
         [](auto& context) {
-            if (auto* localFrame = dynamicDowncast<LocalFrame>(context.document.frame()->mainFrame()))
-                return screenDepthPerComponent(localFrame->view()); 
-            return 8;
+            return screenDepthPerComponent(context.document.frame()->mainFrame().virtualView());
         }
     };
     return schema;
@@ -351,9 +349,7 @@ const FeatureSchema& dynamicRange()
                     return true;
                 if (frame.settings().forcedSupportsHighDynamicRangeValue() == ForcedAccessibilityValue::Off)
                     return false;
-                if (auto* localFrame = dynamicDowncast<LocalFrame>(frame.mainFrame()))
-                    return screenSupportsHighDynamicRange(localFrame->view());
-                return false;
+                return screenSupportsHighDynamicRange(frame.mainFrame().virtualView());
             }();
 
             MatchingIdentifiers identifiers { CSSValueStandard };

Source/WebCore/dom/TreeScope.cpp

@@ -530,11 +530,8 @@ RefPtr<Element> TreeScope::findAnchor(StringView name)
 static Element* focusedFrameOwnerElement(Frame* focusedFrame, LocalFrame* currentFrame)
 {
     for (; focusedFrame; focusedFrame = focusedFrame->tree().parent()) {
-        if (focusedFrame->tree().parent() == currentFrame) {
-            if (auto* localFrame = dynamicDowncast<LocalFrame>(focusedFrame))
-                return localFrame->ownerElement();
-            return nullptr;
-        }
+        if (focusedFrame->tree().parent() == currentFrame)
+            return focusedFrame->ownerElement();
     }
     return nullptr;
 }

Source/WebCore/html/HTMLFrameElementBase.cpp

@@ -161,8 +161,8 @@ void HTMLFrameElementBase::didFinishInsertingNode()
 void HTMLFrameElementBase::didAttachRenderers()
 {
     if (RenderWidget* part = renderWidget()) {
-        if (RefPtr frame = dynamicDowncast<LocalFrame>(contentFrame()))
-            part->setWidget(frame->view());
+        if (RefPtr frame = contentFrame())
+            part->setWidget(frame->virtualView());
     }
 }
 

Source/WebCore/html/MediaElementSession.cpp

@@ -1044,11 +1044,7 @@ static bool isElementRectMostlyInMainFrame(const HTMLMediaElement& element)
     if (!documentFrame)
         return false;
 
-    auto* localFrame = dynamicDowncast<LocalFrame>(documentFrame->mainFrame());
-    if (!localFrame)
-        return false;
-
-    auto mainFrameView = localFrame->view();
+    RefPtr mainFrameView = documentFrame->mainFrame().virtualView();
     if (!mainFrameView)
         return false;
 

Source/WebCore/inspector/InspectorFrontendClientLocal.cpp

@@ -237,9 +237,9 @@ bool InspectorFrontendClientLocal::canAttachWindow()
         return true;
 
     // Don't allow the attach if the window would be too small to accommodate the minimum inspector size.
-    auto* localMainFrame = dynamicDowncast<LocalFrame>(m_inspectedPageController->inspectedPage().mainFrame());
-    unsigned inspectedPageHeight = localMainFrame ? localMainFrame->view()->visibleHeight() : 0;
-    unsigned inspectedPageWidth = localMainFrame ? localMainFrame->view()->visibleWidth() : 0;
+    Ref mainFrame = m_inspectedPageController->inspectedPage().mainFrame();
+    unsigned inspectedPageHeight = mainFrame->virtualView()->visibleHeight();
+    unsigned inspectedPageWidth = mainFrame->virtualView()->visibleWidth();
     unsigned maximumAttachedHeight = inspectedPageHeight * maximumAttachedHeightRatio;
     return minimumAttachedHeight <= maximumAttachedHeight && minimumAttachedWidth <= inspectedPageWidth;
 }
@@ -251,23 +251,15 @@ void InspectorFrontendClientLocal::setDockingUnavailable(bool unavailable)
 
 void InspectorFrontendClientLocal::changeAttachedWindowHeight(unsigned height)
 {
-    auto* localMainFrame = dynamicDowncast<LocalFrame>(m_frontendPage->mainFrame());
-    if (!localMainFrame)
-        return;
-    auto* otherMainFrame = dynamicDowncast<LocalFrame>(m_inspectedPageController->inspectedPage().mainFrame());
-    unsigned totalHeight = localMainFrame->view()->visibleHeight() + (otherMainFrame ? otherMainFrame->view()->visibleHeight() : 0);
+    unsigned totalHeight = m_frontendPage->mainFrame().virtualView()->visibleHeight() + m_inspectedPageController->inspectedPage().mainFrame().virtualView()->visibleHeight();
     unsigned attachedHeight = constrainedAttachedWindowHeight(height, totalHeight);
     m_settings->setProperty(inspectorAttachedHeightSetting, String::number(attachedHeight));
     setAttachedWindowHeight(attachedHeight);
 }
 
 void InspectorFrontendClientLocal::changeAttachedWindowWidth(unsigned width)
 {
-    auto* localMainFrame = dynamicDowncast<LocalFrame>(m_frontendPage->mainFrame());
-    if (!localMainFrame)
-        return;
-    auto* otherMainFrame = dynamicDowncast<LocalFrame>(m_inspectedPageController->inspectedPage().mainFrame());
-    unsigned totalWidth = localMainFrame->view()->visibleWidth() + (otherMainFrame ? localMainFrame->view()->visibleWidth() : 0);
+    unsigned totalWidth = m_frontendPage->mainFrame().virtualView()->visibleWidth() + m_inspectedPageController->inspectedPage().mainFrame().virtualView()->visibleWidth();
     unsigned attachedWidth = constrainedAttachedWindowWidth(width, totalWidth);
     setAttachedWindowWidth(attachedWidth);
 }
@@ -333,8 +325,7 @@ void InspectorFrontendClientLocal::setAttachedWindow(DockSide dockSide)
 
 void InspectorFrontendClientLocal::restoreAttachedWindowHeight()
 {
-    auto* localMainFrame = dynamicDowncast<LocalFrame>(m_inspectedPageController->inspectedPage().mainFrame());
-    unsigned inspectedPageHeight = localMainFrame ? localMainFrame->view()->visibleHeight() : 0;
+    unsigned inspectedPageHeight = m_inspectedPageController->inspectedPage().mainFrame().virtualView()->visibleHeight();
     String value = m_settings->getProperty(inspectorAttachedHeightSetting);
     unsigned preferredHeight = value.isEmpty() ? defaultAttachedHeight : parseIntegerAllowingTrailingJunk<unsigned>(value).value_or(0);
 

Source/WebCore/inspector/InspectorFrontendHost.cpp

@@ -433,8 +433,7 @@ String InspectorFrontendHost::platformVersionName() const
 
 void InspectorFrontendHost::copyText(const String& text)
 {
-    auto* localMainFrame = dynamicDowncast<LocalFrame>(m_frontendPage->mainFrame());
-    auto pageID = m_frontendPage && localMainFrame ? localMainFrame->pageID() : std::nullopt;
+    auto pageID = m_frontendPage ? m_frontendPage->mainFrame().pageID() : std::nullopt;
     Pasteboard::createForCopyAndPaste(PagePasteboardContext::create(WTFMove(pageID)))->writePlainText(text, Pasteboard::CannotSmartReplace);
 }
 

Source/WebCore/inspector/InspectorOverlay.cpp

@@ -106,12 +106,12 @@ static void truncateWithEllipsis(String& string, size_t length)
         string = makeString(StringView(string).left(length), horizontalEllipsis);
 }
 
-static FloatPoint localPointToRootPoint(const LocalFrameView* view, const FloatPoint& point)
+static FloatPoint localPointToRootPoint(const FrameView* view, const FloatPoint& point)
 {
     return view->contentsToRootView(point);
 }
 
-static void contentsQuadToCoordinateSystem(const LocalFrameView* mainView, const LocalFrameView* view, FloatQuad& quad, InspectorOverlay::CoordinateSystem coordinateSystem)
+static void contentsQuadToCoordinateSystem(const FrameView* mainView, const LocalFrameView* view, FloatQuad& quad, InspectorOverlay::CoordinateSystem coordinateSystem)
 {
     quad.setP1(localPointToRootPoint(view, quad.p1()));
     quad.setP2(localPointToRootPoint(view, quad.p2()));
@@ -145,8 +145,7 @@ static void buildRendererHighlight(RenderObject* renderer, const InspectorOverla
 
     highlight.setDataFromConfig(highlightConfig);
     auto* containingView = containingFrame->view();
-    auto* localMainFrame = dynamicDowncast<LocalFrame>(containingFrame->page()->mainFrame());
-    auto* mainView = localMainFrame ? localMainFrame->view() : nullptr;
+    auto* mainView = containingFrame->page()->mainFrame().virtualView();
 
     // (Legacy)RenderSVGRoot should be highlighted through the isBox() code path, all other SVG elements should just dump their absoluteQuads().
     bool isSVGRenderer = renderer->node() && renderer->node()->isSVGElement() && !renderer->isRenderOrLegacyRenderSVGRoot();
@@ -319,8 +318,7 @@ static void drawShapeHighlight(GraphicsContext& context, Node& node, InspectorOv
         return;
 
     auto* containingView = containingFrame->view();
-    auto* localMainFrame = dynamicDowncast<LocalFrame>(containingFrame->page()->mainFrame());
-    auto* mainView = localMainFrame ? localMainFrame->view() : nullptr;
+    auto* mainView = containingFrame->page()->mainFrame().virtualView();
 
     static constexpr auto shapeHighlightColor = SRGBA<uint8_t> { 96, 82, 127, 204 };
 
@@ -402,11 +400,7 @@ void InspectorOverlay::paint(GraphicsContext& context)
     if (!shouldShowOverlay())
         return;
 
-    auto* localMainFrame = dynamicDowncast<LocalFrame>(m_page.mainFrame());
-    if (!localMainFrame)
-        return;
-
-    FloatSize viewportSize = localMainFrame->view()->sizeForVisibleContent();
+    auto viewportSize = m_page.mainFrame().virtualView()->sizeForVisibleContent();
 
     context.clearRect({ FloatPoint::zero(), viewportSize });
 
@@ -603,12 +597,8 @@ void InspectorOverlay::highlightNode(Node* node, const InspectorOverlay::Highlig
 
 void InspectorOverlay::highlightQuad(std::unique_ptr<FloatQuad> quad, const InspectorOverlay::Highlight::Config& highlightConfig)
 {
-    auto* localMainFrame = dynamicDowncast<LocalFrame>(m_page.mainFrame());
-    if (!localMainFrame)
-        return;
-
     if (highlightConfig.usePageCoordinates)
-        *quad -= toIntSize(localMainFrame->view()->scrollPosition());
+        *quad -= toIntSize(m_page.mainFrame().virtualView()->scrollPosition());
 
     m_quadHighlightConfig = highlightConfig;
     m_highlightQuad = WTFMove(quad);
@@ -654,12 +644,7 @@ void InspectorOverlay::update()
         return;
     }
 
-    auto* localMainFrame = dynamicDowncast<LocalFrame>(m_page.mainFrame());
-    if (!localMainFrame)
-        return;
-
-    auto* view = localMainFrame->view();
-    if (!view)
+    if (!m_page.mainFrame().virtualView())
         return;
 
     m_client->highlight();
@@ -683,11 +668,7 @@ void InspectorOverlay::showPaintRect(const FloatRect& rect)
     if (!m_showPaintRects)
         return;
 
-    auto* localMainFrame = dynamicDowncast<LocalFrame>(m_page.mainFrame());
-    if (!localMainFrame)
-        return;
-
-    IntRect rootRect = localMainFrame->view()->contentsToRootView(enclosingIntRect(rect));
+    auto rootRect = m_page.mainFrame().virtualView()->contentsToRootView(enclosingIntRect(rect));
 
     const auto removeDelay = 250_ms;
 
@@ -1530,11 +1511,8 @@ std::optional<InspectorOverlay::Highlight::GridHighlightOverlay> InspectorOverla
     }
 
     constexpr auto translucentLabelBackgroundColor = Color::white.colorWithAlphaByte(230);
-    auto* localMainFrame = dynamicDowncast<LocalFrame>(m_page.mainFrame());
-    if (!localMainFrame)
-        return { };
 
-    auto* pageView = localMainFrame->view();
+    RefPtr pageView = m_page.mainFrame().virtualView();
     if (!pageView)
         return { };
     FloatRect viewportBounds = { { 0, 0 }, pageView->sizeForVisibleContent() };

Source/WebCore/inspector/agents/InspectorPageAgent.cpp

@@ -1045,10 +1045,7 @@ void InspectorPageAgent::didPaint(RenderObject& renderer, const LayoutRect& rect
     Ref localFrame = view->frame();
     if (!localFrame->isMainFrame()) {
         IntRect rootViewRect = view->contentsToRootView(snappedIntRect(absoluteRect));
-        auto* localMainFrame = dynamicDowncast<LocalFrame>(localFrame->mainFrame());
-        if (!localMainFrame)
-            return;
-        rootRect = localMainFrame->view()->rootViewToContents(rootViewRect);
+        rootRect = localFrame->mainFrame().virtualView()->rootViewToContents(rootViewRect);
     }
 
     if (m_client->overridesShowPaintRects()) {

Source/WebCore/loader/FrameLoader.cpp

@@ -1265,10 +1265,8 @@ void FrameLoader::completed()
 {
     Ref frame = m_frame.get();
 
-    for (RefPtr descendant = frame->tree().traverseNext(m_frame.ptr()); descendant; descendant = descendant->tree().traverseNext(m_frame.ptr())) {
-        if (RefPtr localDescendant = dynamicDowncast<LocalFrame>(*descendant))
-            localDescendant->navigationScheduler().startTimer();
-    }
+    for (RefPtr descendant = frame->tree().traverseNext(m_frame.ptr()); descendant; descendant = descendant->tree().traverseNext(m_frame.ptr()))
+        descendant->navigationScheduler().startTimer();
 
     if (RefPtr parent = m_frame->tree().parent()) {
         if (RefPtr localParent = dynamicDowncast<LocalFrame>(parent.releaseNonNull()))

Source/WebCore/page/DragController.cpp

@@ -1367,12 +1367,9 @@ void DragController::beginDrag(DragItem dragItem, LocalFrame& frame, const IntPo
     m_didInitiateDrag = true;
     m_dragInitiator = frame.document();
 
-    auto* localMainFrame = dynamicDowncast<LocalFrame>(m_page.mainFrame());
-    if (!localMainFrame)
-        return;
     // Protect this frame and view, as a load may occur mid drag and attempt to unload this frame
-    Ref protectedLocalMainFrame(*localMainFrame);
-    RefPtr viewProtector = protectedLocalMainFrame->view();
+    Ref protectedLocalMainFrame(m_page.mainFrame());
+    RefPtr viewProtector = protectedLocalMainFrame->virtualView();
 
     auto mouseDownPointInRootViewCoordinates = viewProtector->rootViewToContents(frame.view()->contentsToRootView(mouseDownPoint));
     auto mouseDraggedPointInRootViewCoordinates = viewProtector->rootViewToContents(frame.view()->contentsToRootView(mouseDraggedPoint));

Source/WebCore/page/FocusController.cpp

@@ -504,10 +504,8 @@ void FocusController::setFocusedInternal(bool focused)
     if (!isFocused())
         focusedOrMainFrame().eventHandler().stopAutoscrollTimer();
 
-    if (!focusedFrame()) {
-        if (auto* localMainFrame = dynamicDowncast<LocalFrame>(m_page.mainFrame()))
-            setFocusedFrame(localMainFrame);
-    }
+    if (!focusedFrame())
+        setFocusedFrame(&m_page.mainFrame());
 
     auto* focusedFrame = focusedLocalFrame();
     if (focusedFrame && focusedFrame->view()) {
@@ -632,7 +630,7 @@ bool FocusController::advanceFocusInDocumentOrder(FocusDirection direction, Keyb
             return false;
 
         document->setFocusedElement(nullptr);
-        setFocusedFrame(dynamicDowncast<LocalFrame>(owner.contentFrame()));
+        setFocusedFrame(owner.contentFrame());
         return true;
     }
 
@@ -1029,17 +1027,13 @@ static void contentAreaDidShowOrHide(ScrollableArea* scrollableArea, bool didSho
 
 void FocusController::setIsVisibleAndActiveInternal(bool contentIsVisible)
 {
-    auto* localMainFrame = dynamicDowncast<LocalFrame>(m_page.mainFrame());
-    if (!localMainFrame)
-        return;
-
-    auto* view = localMainFrame->view();
+    auto* view = m_page.mainFrame().virtualView();
     if (!view)
         return;
 
     contentAreaDidShowOrHide(view, contentIsVisible);
 
-    for (Frame* frame = localMainFrame; frame; frame = frame->tree().traverseNext()) {
+    for (auto* frame = &m_page.mainFrame(); frame; frame = frame->tree().traverseNext()) {
         auto* localFrame = dynamicDowncast<LocalFrame>(frame);
         if (!localFrame)
             continue;

Source/WebCore/page/IntersectionObserver.cpp

@@ -349,7 +349,7 @@ auto IntersectionObserver::computeIntersectionState(const IntersectionObserverRe
 
         ASSERT(frameView.frame().isMainFrame());
         // FIXME: Handle the case of an implicit-root observer that has a target in a different frame tree.
-        if (dynamicDowncast<LocalFrame>(targetRenderer->frame().mainFrame()) != &frameView.frame())
+        if (targetRenderer->frame().mainFrame() != frameView.frame())
             return;
 
         intersectionState.canComputeIntersection = true;

Source/WebCore/page/LocalDOMWindow.cpp

@@ -329,10 +329,7 @@ void LocalDOMWindow::dispatchAllPendingUnloadEvents()
 // 5) Translate the window rect coordinates to be within the coordinate space of the screen.
 FloatRect LocalDOMWindow::adjustWindowRect(Page& page, const FloatRect& pendingChanges)
 {
-    RefPtr localMainFrame = dynamicDowncast<LocalFrame>(page.mainFrame());
-    if (!localMainFrame)
-        return FloatRect();
-    FloatRect screen = screenAvailableRect(localMainFrame->view());
+    FloatRect screen = screenAvailableRect(page.mainFrame().virtualView());
     FloatRect window = page.chrome().windowRect();
 
     // Make sure we're in a valid state before adjusting dimensions.
@@ -1846,11 +1843,8 @@ void LocalDOMWindow::moveTo(int x, int y) const
 
     CheckedPtr page = frame()->page();
     auto fr = page->chrome().windowRect();
-    RefPtr localMainFrame = dynamicDowncast<LocalFrame>(page->mainFrame());
-    if (!localMainFrame)
-        return;
 
-    auto sr = screenAvailableRect(localMainFrame->view());
+    auto sr = screenAvailableRect(page->mainFrame().virtualView());
     fr.setLocation(sr.location());
     auto update = fr;
     update.move(x, y);

Source/WebCore/page/LocalFrameView.cpp

@@ -3007,11 +3007,7 @@ bool LocalFrameView::shouldUpdateCompositingLayersAfterScrolling() const
     if (!page)
         return true;
 
-    auto* localMainFrame = dynamicDowncast<LocalFrame>(page->mainFrame());
-    if (!localMainFrame)
-        return true;
-
-    if (localMainFrame != m_frame.ptr())
+    if (page->mainFrame() != m_frame)
         return true;
 
     auto scrollingCoordinator = this->scrollingCoordinator();