::backdrop UA styles should be appended unconditionally

https://bugs.webkit.org/show_bug.cgi?id=248456 rdar://102748281 Reviewed by Darin Adler. * Source/WebCore/css/dialog.css: (dialog::backdrop): (::backdrop): Deleted. * Source/WebCore/css/html.css: (::backdrop): * Source/WebCore/rendering/updating/RenderTreeUpdaterGeneratedContent.cpp: (WebCore::RenderTreeUpdater::GeneratedContent::updateBackdropRenderer): Canonical link: https://commits.webkit.org/257320@main
WebKit · Dec 3, 2022 · fdf33fd · fdf33fd
1 parent fb7087c
commit fdf33fd
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Showing 3 changed files with 21 additions and 13 deletions.
diff --git a/Source/WebCore/css/dialog.css b/Source/WebCore/css/dialog.css
@@ -29,12 +29,3 @@ dialog:modal {
 dialog::backdrop {
     background: rgba(0, 0, 0, 0.1);
 }
-
-::backdrop {
-    display: block;
-    position: fixed;
-    top: 0;
-    left: 0;
-    right: 0;
-    bottom: 0;
-}
diff --git a/Source/WebCore/css/html.css b/Source/WebCore/css/html.css
@@ -112,6 +112,14 @@ abbr[title], acronym[title] {
     text-decoration: dotted underline;
 }
 
+/* ::backdrop */
+
+::backdrop {
+    display: block;
+    position: fixed;
+    inset: 0;
+}
+
 /* media elements */
 
 body:-webkit-full-page-media {

diff --git a/Source/WebCore/rendering/updating/RenderTreeUpdaterGeneratedContent.cpp b/Source/WebCore/rendering/updating/RenderTreeUpdaterGeneratedContent.cpp
@@ -177,13 +177,22 @@ void RenderTreeUpdater::GeneratedContent::updateBackdropRenderer(RenderElement&
 {
     if (!renderer.canHaveGeneratedChildren())
         return;
-    // ::backdrop does not inherit style, hence using the view style as parent style
-    auto style = renderer.getCachedPseudoStyle(PseudoId::Backdrop, &renderer.view().style());
 
-    // Destroy ::backdrop if new element no longer is in top layer, or if it is hidden
-    if ((renderer.element() && !renderer.element()->isInTopLayer()) || !style || style->display() == DisplayType::None) {
+    auto destroyBackdropIfNeeded = [&renderer, this]() {
         if (WeakPtr backdropRenderer = renderer.backdropRenderer())
             m_updater.m_builder.destroy(*backdropRenderer);
+    };
+
+    // Intentionally bail out early here to avoid computing the style.
+    if (!renderer.element() || !renderer.element()->isInTopLayer()) {
+        destroyBackdropIfNeeded();
+        return;
+    }
+
+    // ::backdrop does not inherit style, hence using the view style as parent style
+    auto style = renderer.getCachedPseudoStyle(PseudoId::Backdrop, &renderer.view().style());
+    if (!style || style->display() == DisplayType::None) {
+        destroyBackdropIfNeeded();
         return;
     }