Bug 1764721 - Content skipped via `content-visibility` should not be focusable r=emilio

Differential Revision: https://phabricator.services.mozilla.com/D143723

layout/generic/nsIFrame.cpp

@@ -408,6 +408,8 @@ bool nsIFrame::IsVisibleConsideringAncestors(uint32_t aFlags) const {
     nsView* view = frame->GetView();
     if (view && view->GetVisibility() == nsViewVisibility_kHide) return false;
 
+    if (this != frame && frame->IsContentHidden()) return false;
+
     nsIFrame* parent = frame->GetParent();
     nsDeckFrame* deck = do_QueryFrame(parent);
     if (deck) {

testing/web-platform/meta/css/css-contain/content-visibility/content-visibility-035.html.ini

@@ -1,7 +0,0 @@
-[content-visibility-035.html]
-  expected:
-    if (os == "win") and not debug: [OK, TIMEOUT]
-  [Testing focus and force layout on element with hidden flat-tree ancestor]
-    expected:
-      if (os == "win") and not debug: [FAIL, TIMEOUT]
-      FAIL