Bug 1998438 - Don't call InitPrimaryFrame() twice for subdocuments. r=layout-reviewers,dholbert

emilio · emilio · commit e1a20b25e5e4 · 2025-11-11T01:28:37.000Z
nsSubDocumentFrame::Init calls SetPrimaryFrame relatively early, and we're calling InitPrimaryFrame() twice because of that. Differential Revision: https://phabricator.services.mozilla.com/D271923
diff --git a/layout/generic/nsIFrame.h b/layout/generic/nsIFrame.h
@@ -2579,6 +2579,9 @@ class nsIFrame : public nsQueryFrame {
   bool IsPrimaryFrame() const { return mIsPrimaryFrame; }
 
   void SetIsPrimaryFrame(bool aIsPrimary) {
+    if (mIsPrimaryFrame == aIsPrimary) {
+      return;
+    }
     mIsPrimaryFrame = aIsPrimary;
     if (aIsPrimary) {
       InitPrimaryFrame();
diff --git a/testing/web-platform/tests/css/css-anchor-position/iframe-anchor-name-crash.html b/testing/web-platform/tests/css/css-anchor-position/iframe-anchor-name-crash.html
@@ -0,0 +1,13 @@
+<!doctype html>
+<link rel="help" href="https://bugzilla.mozilla.org/show_bug.cgi?id=1998438">
+<style>
+* {
+    anchor-name: --anchor-name_0;
+}
+</style>
+<script>
+window.addEventListener("load", async () => {
+  const iframe = document.createElementNS("http://www.w3.org/1999/xhtml", "iframe")
+  document.documentElement.appendChild(iframe)
+})
+</script>
