perf(cache): avoid Request and Response initialization (nodejs#2610)

lib/cache/cache.js

@@ -7,6 +7,7 @@ const { kHeadersList } = require('../core/symbols')
 const { webidl } = require('../fetch/webidl')
 const { Response, cloneResponse } = require('../fetch/response')
 const { Request } = require('../fetch/request')
+const { Headers } = require('../fetch/headers')
 const { kState, kHeaders, kGuard, kRealm } = require('../fetch/symbols')
 const { fetching } = require('../fetch/index')
 const { urlIsHttpHttpsScheme, createDeferredPromise, readAllBytes } = require('../fetch/util')
@@ -502,8 +503,9 @@ class Cache {
 
       // 5.4.2
       for (const request of requests) {
-        const requestObject = new Request('https://a')
+        const requestObject = new Request(kConstruct)
         requestObject[kState] = request
+        requestObject[kHeaders] = new Headers(kConstruct)
         requestObject[kHeaders][kHeadersList] = request.headersList
         requestObject[kHeaders][kGuard] = 'immutable'
         requestObject[kRealm] = request.client
@@ -782,8 +784,9 @@ class Cache {
     // 5.5.2
     for (const response of responses) {
       // 5.5.2.1
-      const responseObject = new Response(null)
+      const responseObject = new Response(kConstruct)
       responseObject[kState] = response
+      responseObject[kHeaders] = new Headers(kConstruct)
       responseObject[kHeaders][kHeadersList] = response.headersList
       responseObject[kHeaders][kGuard] = 'immutable'