--- a/dom/base/nsDocument.cpp
+++ b/dom/base/nsDocument.cpp
@@ -12009,21 +12009,46 @@ nsIDocument::GetTopLevelContentDocument(
 
     nsIDocument* candidate = parent->GetParentDocument();
     parent = static_cast<nsDocument*>(candidate);
   } while (parent);
 
   return parent;
 }
 
+static bool
+MightBeChromeScheme(nsIURI* aURI)
+{
+  MOZ_ASSERT(aURI);
+  bool isChrome = true;
+  aURI->SchemeIs("chrome", &isChrome);
+  return isChrome;
+}
+
+static bool
+MightBeAboutOrChromeScheme(nsIURI* aURI)
+{
+  MOZ_ASSERT(aURI);
+  bool isAbout = true;
+  aURI->SchemeIs("about", &isAbout);
+  return isAbout || MightBeChromeScheme(aURI);
+}
+
 void
 nsIDocument::PropagateUseCounters(nsIDocument* aParentDocument)
 {
   MOZ_ASSERT(this != aParentDocument);
 
+  // Don't count chrome resources, even in the web content.
+  nsCOMPtr<nsIURI> uri;
+  NodePrincipal()->GetURI(getter_AddRefs(uri));
+  if (!uri || MightBeChromeScheme(uri)) {
+    return;
+  }
+
   // What really matters here is that our use counters get propagated as
   // high up in the content document hierarchy as possible.  So,
   // starting with aParentDocument, we need to find the toplevel content
   // document, and propagate our use counters into its
   // mChildDocumentUseCounters.
   nsIDocument* contentParent = aParentDocument->GetTopLevelContentDocument();
 
   if (!contentParent) {
@@ -12100,27 +12125,16 @@ nsIDocument::InlineScriptAllowedByCSP()
                                        0,             // aLineNumber
                                        &allowsInlineScript);
     NS_ENSURE_SUCCESS(rv, true);
   }
   return allowsInlineScript;
 }
 
 static bool
-MightBeAboutOrChromeScheme(nsIURI* aURI)
-{
-  MOZ_ASSERT(aURI);
-  bool isAbout = true;
-  bool isChrome = true;
-  aURI->SchemeIs("about", &isAbout);
-  aURI->SchemeIs("chrome", &isChrome);
-  return isAbout || isChrome;
-}
-
-static bool
 ReportExternalResourceUseCounters(nsIDocument* aDocument, void* aData)
 {
   const auto reportKind
     = nsDocument::UseCounterReportKind::eIncludeExternalResources;
   static_cast<nsDocument*>(aDocument)->ReportUseCounters(reportKind);
   return true;
 }