chore: remove DOMWorld definition from externs.d.ts (#5767)

Missed in the initial work to migrate DOMWorld to TypeScript.

src/ExecutionContext.ts

@@ -17,16 +17,17 @@
 import {helper, assert} from './helper';
 import {createJSHandle, JSHandle, ElementHandle} from './JSHandle';
 import {CDPSession} from './Connection';
+import {DOMWorld} from './DOMWorld';
 
 export const EVALUATION_SCRIPT_URL = '__puppeteer_evaluation_script__';
 const SOURCE_URL_REGEX = /^[\040\t]*\/\/[@#] sourceURL=\s*(\S*?)\s*$/m;
 
 export class ExecutionContext {
   _client: CDPSession;
-  _world: Puppeteer.DOMWorld;
+  _world: DOMWorld;
   _contextId: number;
 
-  constructor(client: CDPSession, contextPayload: Protocol.Runtime.ExecutionContextDescription, world: Puppeteer.DOMWorld) {
+  constructor(client: CDPSession, contextPayload: Protocol.Runtime.ExecutionContextDescription, world: DOMWorld) {
     this._client = client;
     this._world = world;
     this._contextId = contextPayload.id;

src/externs.d.ts

@@ -1,7 +1,6 @@
 import {Target as RealTarget} from './Target.js';
 import {Page as RealPage} from './Page.js';
 import {Frame as RealFrame, FrameManager as RealFrameManager}  from './FrameManager.js';
-import {DOMWorld as RealDOMWorld}  from './DOMWorld.js';
 import { NetworkManager as RealNetworkManager, Request as RealRequest, Response as RealResponse } from './NetworkManager.js';
 import * as child_process from 'child_process';
 declare global {
@@ -10,7 +9,6 @@ declare global {
     export class Frame extends RealFrame {}
     export class FrameManager extends RealFrameManager {}
     export class NetworkManager extends RealNetworkManager {}
-    export class DOMWorld extends RealDOMWorld {}
     export class Page extends RealPage { }
     export class Response extends RealResponse { }
     export class Request extends RealRequest { }