From ce474db990f855e9c764724d0e6efd84fa522840 Mon Sep 17 00:00:00 2001
From: Russell Bicknell <bicknellr@google.com>
Date: Wed, 1 Jun 2022 14:52:14 -0700
Subject: [PATCH] Adds Trusted Types support for reflected boolean properties.

---
 lib/mixins/properties-changed.js | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/lib/mixins/properties-changed.js b/lib/mixins/properties-changed.js
index 9e481d67..ea06942a 100644
--- a/lib/mixins/properties-changed.js
+++ b/lib/mixins/properties-changed.js
@@ -550,7 +550,9 @@ export const PropertiesChanged = dedupingMixin(
     _serializeValue(value) {
       switch (typeof value) {
         case 'boolean':
-          return value ? '' : undefined;
+          return value ?
+              (window.trustedTypes ? window.trustedTypes.emptyScript : '') :
+              undefined;
         default:
           return value != null ? value.toString() : undefined;
       }