Refactor <webview> tag tests (#12886)

spec/fixtures/module/preload-node-off.js

@@ -1,6 +1,12 @@
 setImmediate(function () {
   try {
-    console.log([typeof process, typeof setImmediate, typeof global, typeof Buffer].join(' '))
+    const types = {
+      process: typeof process,
+      setImmediate: typeof setImmediate,
+      global: typeof global,
+      Buffer: typeof Buffer
+    }
+    console.log(JSON.stringify(types))
   } catch (e) {
     console.log(e.message)
   }