chore: return Promise<any> in {page,context}.route (#20005)

Fixes https://github.com/microsoft/playwright/issues/19855
Closes https://github.com/microsoft/playwright/pull/19856

docs/src/api/class-browsercontext.md

@@ -1060,7 +1060,7 @@ it gets merged via the [`new URL()`](https://developer.mozilla.org/en-US/docs/We
 ### param: BrowserContext.route.handler
 * since: v1.8
 * langs: js, python
-- `handler` <[function]\([Route], [Request]\)>
+- `handler` <[function]\([Route], [Request]\): [Promise<any>|any]>
 
 handler function to route the request.
 

docs/src/api/class-page.md

@@ -3138,7 +3138,7 @@ it gets merged via the [`new URL()`](https://developer.mozilla.org/en-US/docs/We
 ### param: Page.route.handler
 * since: v1.8
 * langs: js, python
-- `handler` <[function]\([Route], [Request]\)>
+- `handler` <[function]\([Route], [Request]\): [Promise<any>|any]>
 
 handler function to route the request.
 

packages/playwright-core/src/client/network.ts

@@ -422,7 +422,7 @@ export class Route extends ChannelOwner<channels.RouteChannel> implements api.Ro
   }
 }
 
-export type RouteHandlerCallback = (route: Route, request: Request) => void;
+export type RouteHandlerCallback = (route: Route, request: Request) => Promise<any> | void;
 
 export type ResourceTiming = {
   startTime: number;

packages/playwright-core/types/types.d.ts

@@ -3564,7 +3564,7 @@ export interface Page {
    * @param handler handler function to route the request.
    * @param options
    */
-  route(url: string|RegExp|((url: URL) => boolean), handler: ((route: Route, request: Request) => void), options?: {
+  route(url: string|RegExp|((url: URL) => boolean), handler: ((route: Route, request: Request) => Promise<any>|any), options?: {
     /**
      * How often a route should be used. By default it will be used every time.
      */
@@ -8041,7 +8041,7 @@ export interface BrowserContext {
    * @param handler handler function to route the request.
    * @param options
    */
-  route(url: string|RegExp|((url: URL) => boolean), handler: ((route: Route, request: Request) => void), options?: {
+  route(url: string|RegExp|((url: URL) => boolean), handler: ((route: Route, request: Request) => Promise<any>|any), options?: {
     /**
      * How often a route should be used. By default it will be used every time.
      */

utils/generate_types/test/test.ts

@@ -139,6 +139,8 @@ playwright.chromium.launch().then(async browser => {
     else route.continue();
   });
 
+  await page.route('**/*', route => route.continue());
+
   await page.route(str => {
     return true;
   }, (route, request) => {