LibWeb: Implement 'Is non-secure context' AO

Author: https://github.com/linusg
Commit: 8db64a8704
Pull-request: https://github.com/SerenityOS/serenity/pull/15795
Reviewed-by: https://github.com/ADKaster
Reviewed-by: https://github.com/awesomekling
Reviewed-by: https://github.com/davidot ✅

Userland/Libraries/LibWeb/HTML/Scripting/Environments.cpp

@@ -423,4 +423,11 @@ bool is_secure_context(Environment const& environment)
     return false;
 }
 
+// https://html.spec.whatwg.org/multipage/webappapis.html#non-secure-context
+bool is_non_secure_context(Environment const& environment)
+{
+    // An environment is a non-secure context if it is not a secure context.
+    return !is_secure_context(environment);
+}
+
 }