types: better type definition for internal utils (#43070)

The PR removes some `as unknown as` assertions by improving type
definitions.

packages/next/client/components/app-router.tsx

@@ -168,7 +168,7 @@ function Router({
         // This is safe to do as canonicalUrl can't be rendered, it's only used to control the history updates in the useEffect further down in this file.
         typeof window !== 'undefined'
           ? // window.location does not have the same type as URL but has all the fields createHrefFromUrl needs.
-            createHrefFromUrl(window.location as unknown as URL)
+            createHrefFromUrl(window.location)
           : initialCanonicalUrl,
     }
   }, [children, initialCanonicalUrl, initialTree])

packages/next/client/components/reducer.ts

@@ -45,7 +45,9 @@ function readRecordValue<T>(thenable: Promise<T>): T {
   }
 }
 
-export function createHrefFromUrl(url: URL): string {
+export function createHrefFromUrl(
+  url: Pick<URL, 'pathname' | 'search' | 'hash'>
+): string {
   return url.pathname + url.search + url.hash
 }
 

packages/next/client/request-idle-callback.ts

@@ -4,14 +4,14 @@ export const requestIdleCallback =
     self.requestIdleCallback.bind(window)) ||
   function (cb: IdleRequestCallback): number {
     let start = Date.now()
-    return setTimeout(function () {
+    return self.setTimeout(function () {
       cb({
         didTimeout: false,
         timeRemaining: function () {
           return Math.max(0, 50 - (Date.now() - start))
         },
       })
-    }, 1) as unknown as number
+    }, 1)
   }
 
 export const cancelIdleCallback =