Restructure to avoid internal window.Turbo access

Replace accessing the `recentRequests` property through the
`window.Turbo.session` object.

In its place, restructure the object's dependency graph so that the
`http/fetch` module constructs the `LimitedSet` instance, and the
`Session` accepts that instance as a property.

src/core/index.js

@@ -3,9 +3,9 @@ import { PageRenderer } from "./drive/page_renderer"
 import { PageSnapshot } from "./drive/page_snapshot"
 import { FrameRenderer } from "./frames/frame_renderer"
 import { FormSubmission } from "./drive/form_submission"
-import { fetch } from "../http/fetch"
+import { fetch, recentRequests } from "../http/fetch"
 
-const session = new Session()
+const session = new Session(recentRequests)
 const { cache, navigator } = session
 export { navigator, session, cache, PageRenderer, PageSnapshot, FrameRenderer, fetch }
 

src/core/session.js

@@ -16,7 +16,6 @@ import { clearBusyState, dispatch, findClosestRecursively, getVisitAction, markA
 import { PageView } from "./drive/page_view"
 import { FrameElement } from "../elements/frame_element"
 import { Preloader } from "./drive/preloader"
-import { LimitedSet } from "./drive/limited_set"
 import { Cache } from "./cache"
 
 export class Session {
@@ -36,14 +35,17 @@ export class Session {
   frameRedirector = new FrameRedirector(this, document.documentElement)
   streamMessageRenderer = new StreamMessageRenderer()
   cache = new Cache(this)
-  recentRequests = new LimitedSet(20)
 
   drive = true
   enabled = true
   progressBarDelay = 500
   started = false
   formMode = "on"
 
+  constructor(recentRequests) {
+    this.recentRequests = recentRequests
+  }
+
   start() {
     if (!this.started) {
       this.pageObserver.start()

src/http/fetch.js

@@ -1,9 +1,12 @@
 import { uuid } from "../util"
+import { LimitedSet } from "../core/drive/limited_set"
+
+export const recentRequests = new LimitedSet(20)
 
 export function fetch(url, options = {}) {
   const modifiedHeaders = new Headers(options.headers || {})
   const requestUID = uuid()
-  window.Turbo.session.recentRequests.add(requestUID)
+  recentRequests.add(requestUID)
   modifiedHeaders.append("X-Turbo-Request-Id", requestUID)
 
   return window.fetch(url, {