await for FetchRequest delegate to handle response

Closes [#884]

Despite the fact that `Visit` and `FrameController` are `FetchRequest`
delegate classes that implement their delegate methods asynchronously on
success ([Visit.requestSucceededWithResponse][] and
[FrameController.requestSucceededWithResponse][]) and on failure
([Visit.requestFailedWithResponse][]) and
[FrameController.requestFailedWithResponse][]), the `async
FetchRequest.receive` method doesn't use the `await` keyword to wait for
those delegates to finish handling their callbacks.

This commit adds those `await` clauses.

[Visit.requestSucceededWithResponse]: https://github.com/hotwired/turbo/blob/c207f5b25758e4a084e8ae42e49712b91cf37114/src/core/drive/visit.js#L297
[FrameController.requestSucceededWithResponse]: https://github.com/hotwired/turbo/blob/c207f5b25758e4a084e8ae42e49712b91cf37114/src/core/frames/frame_controller.js#L210
[Visit.requestFailedWithResponse]: https://github.com/hotwired/turbo/blob/c207f5b25758e4a084e8ae42e49712b91cf37114/src/core/drive/visit.js#L311
[FrameController.requestFailedWithResponse]: https://github.com/hotwired/turbo/blob/c207f5b25758e4a084e8ae42e49712b91cf37114/src/core/frames/frame_controller.js#L215

[#884]: #884

src/core/drive/visit.js

@@ -159,7 +159,7 @@ export class Visit {
       this.simulateRequest()
     } else if (!this.request && await this.shouldIssueRequest()) {
       this.request = new FetchRequest(this, FetchMethod.get, this.location)
-      this.request.perform()
+      await this.request.perform()
     }
   }
 

src/core/frames/frame_controller.js

@@ -321,7 +321,7 @@ export class FrameController {
     }
   }
 
-  async #visit(url) {
+  #visit(url) {
     const request = new FetchRequest(this, FetchMethod.get, url, new URLSearchParams(), this.element)
 
     this.#currentFetchRequest?.cancel()
@@ -333,7 +333,7 @@ export class FrameController {
         this.#currentFetchRequest = null
         resolve()
       }
-      request.perform()
+      return request.perform()
     })
   }
 

src/http/fetch_request.js

@@ -124,7 +124,7 @@ export class FetchRequest {
     try {
       this.delegate.requestStarted(this)
       const response = await fetch(this.url.href, fetchOptions)
-      return await this.receive(response)
+      return this.receive(response)
     } catch (error) {
       if (error.name !== "AbortError") {
         if (this.#willDelegateErrorHandling(error)) {
@@ -147,9 +147,9 @@ export class FetchRequest {
     if (event.defaultPrevented) {
       this.delegate.requestPreventedHandlingResponse(this, fetchResponse)
     } else if (fetchResponse.succeeded) {
-      this.delegate.requestSucceededWithResponse(this, fetchResponse)
+      await this.delegate.requestSucceededWithResponse(this, fetchResponse)
     } else {
-      this.delegate.requestFailedWithResponse(this, fetchResponse)
+      await this.delegate.requestFailedWithResponse(this, fetchResponse)
     }
     return fetchResponse
   }