3 files changed, 19 insertions, 11 deletions
diff --git a/dom/base/crashtests/1419799.html b/dom/base/crashtests/1419799.html
new file mode 100644
index 0000000000..b6d34a1a97
--- /dev/null
+++ b/dom/base/crashtests/1419799.html
@@ -0,0 +1,17 @@
+<html>
+  <head>
+    <script>
+      try { o1 = document.createElement('textarea') } catch(e) { }
+      try { o2 = document.createElement('div') } catch(e) { }
+      try { o3 = document.createElement('map') } catch(e) { }
+      try { document.documentElement.appendChild(o2) } catch(e) { }
+      try { o2.appendChild(o1) } catch(e) { }
+      try { document.documentElement.getClientRects() } catch(e) { }
+      try { o4 = o2.attachShadow({ mode: "open" }); } catch(e) { }
+      try { o1.appendChild(o3) } catch(e) { }
+      try { o5 = o3.parentElement } catch(e) { }
+      try { o3.outerHTML = "\n" } catch(e) { }
+      try { o4.prepend("", o5, "") } catch(e) { }
+    </script>
+  </head>
+</html>
diff --git a/dom/base/crashtests/crashtests.list b/dom/base/crashtests/crashtests.list
index d8b5e9625a..8b115fd4de 100644
--- a/dom/base/crashtests/crashtests.list
+++ b/dom/base/crashtests/crashtests.list
@@ -210,3 +210,4 @@ load 1251361.html
 load 1304437.html
 pref(clipboard.autocopy,true) load 1385272-1.html
 pref(dom.webcomponents.customelements.enabled,true) load 1341693.html
+pref(dom.webcomponents.enabled,true) load 1419799.html
diff --git a/dom/base/nsContentUtils.cpp b/dom/base/nsContentUtils.cpp
index 62be71b4ab..502c409778 100644
--- a/dom/base/nsContentUtils.cpp
+++ b/dom/base/nsContentUtils.cpp
@@ -4955,17 +4955,7 @@ nsContentUtils::IsInSameAnonymousTree(const nsINode* aNode,
     return aContent->GetBindingParent() == nullptr;
   }
 
-  const nsIContent* nodeAsContent = static_cast<const nsIContent*>(aNode);
-
-  // For nodes in a shadow tree, it is insufficient to simply compare
-  // the binding parent because a node may host multiple ShadowRoots,
-  // thus nodes in different shadow tree may have the same binding parent.
-  if (aNode->IsInShadowTree()) {
-    return nodeAsContent->GetContainingShadow() ==
-      aContent->GetContainingShadow();
-  }
-
-  return nodeAsContent->GetBindingParent() == aContent->GetBindingParent();
+  return aNode->AsContent()->GetBindingParent() == aContent->GetBindingParent();
 }
 
 class AnonymousContentDestroyer : public Runnable {