use devalue instead of serialize-javascript - fixes #112

test/app/routes/preload-values/set.html

@@ -0,0 +1,11 @@
+<h1>{{set.has('x')}}</h1>
+
+<script>
+	export default {
+		preload() {
+			return {
+				set: new Set(['x'])
+			};
+		}
+	};
+</script>