Add vscode namespace in webview

From discussion around #48540

extensions/markdown-language-features/preview-src/messaging.ts

@@ -5,15 +5,17 @@
 
 import { getSettings } from './settings';
 
+declare var vscode: any;
+
 /**
  * Post a message to the markdown extension
  */
 export function postMessage(type: string, body: object) {
-	window.parent.postMessage({
+	vscode.postMessage({
 		type,
 		source: getSettings().source,
 		body
-	}, '*');
+	});
 }
 
 /**

src/vs/workbench/parts/webview/electron-browser/webview-pre.js

@@ -10,7 +10,7 @@
 	const ipcRenderer = require('electron').ipcRenderer;
 
 
-	const registerVscodeResourceScheme = (function() {
+	const registerVscodeResourceScheme = (function () {
 		let hasRegistered = false;
 		return () => {
 			if (hasRegistered) {
@@ -174,6 +174,28 @@
 				newDocument.head.appendChild(baseElement);
 			}
 
+			// apply default script
+			if (enableWrappedPostMessage) {
+				const defaultScript = newDocument.createElement('script');
+				defaultScript.textContent = `
+					const vscode = Object.freeze((function() {
+						const originalPostMessage = window.parent.postMessage.bind(window.parent);
+						return {
+							postMessage: function(msg) {
+								return originalPostMessage(msg, '*');
+							}
+						};
+					})());
+					delete window.parent;
+				`;
+
+				if (newDocument.head.hasChildNodes()) {
+					newDocument.head.insertBefore(defaultScript, newDocument.head.firstChild);
+				} else {
+					newDocument.head.appendChild(defaultScript);
+				}
+			}
+
 			// apply default styles
 			const defaultStyles = newDocument.createElement('style');
 			defaultStyles.id = '_defaultStyles';