spec: fix final node and chromium specs after assert change

spec/assert-helpers.js

@@ -1,5 +1,16 @@
+function resolveSingleObjectGetters (object) {
+  if (object && typeof object === 'object') {
+    const newObject = {}
+    for (const key in object) {
+      newObject[key] = resolveGetters(object[key])[0]
+    }
+    return newObject
+  }
+  return object
+}
+
 function resolveGetters (...args) {
-  return args.map(o => JSON.parse(JSON.stringify(o)))
+  return args.map(resolveSingleObjectGetters)
 }
 
 module.exports = {