Only disable onbeforeunload if using iframe based webviews

Fixes #122818

src/vs/workbench/contrib/webview/browser/pre/main.js

@@ -23,6 +23,7 @@ const isSafari = navigator.vendor && navigator.vendor.indexOf('Apple') > -1 &&
 
 const searchParams = new URL(location.toString()).searchParams;
 const ID = searchParams.get('id');
+const isUsingWebviewTag = searchParams.has('isUsingWebviewTag');
 
 /**
  * Use polling to track focus of main webview and iframes within the webview
@@ -188,6 +189,7 @@ function getVsCodeApiScript(allowMultipleAPIAcquire, useParentPostMessage, state
 			delete window.top;
 			delete window.frameElement;
 
+			if (!${isUsingWebviewTag}) {
 				// Try to block webviews from cancelling unloads.
 				// This blocking is not perfect but should block common patterns
 				(function() {
@@ -216,6 +218,7 @@ function getVsCodeApiScript(allowMultipleAPIAcquire, useParentPostMessage, state
 						}
 					}
 				})();
+			}
 		`;
 }
 

src/vs/workbench/contrib/webview/electron-browser/webviewElement.ts

@@ -156,7 +156,7 @@ export class ElectronWebviewBasedWebview extends BaseWebview<WebviewTag> impleme
 		// and not the `vscode-file` URI because preload scripts are loaded
 		// via node.js from the main side and only allow `file:` protocol
 		this.element!.preload = FileAccess.asFileUri('./pre/electron-index.js', require).toString(true);
-		this.element!.src = `${Schemas.vscodeWebview}://${this.id}/electron-browser-index.html?platform=electron&id=${this.id}&vscode-resource-origin=${encodeURIComponent(this.webviewResourceEndpoint)}`;
+		this.element!.src = `${Schemas.vscodeWebview}://${this.id}/electron-browser-index.html?platform=electron&isUsingWebviewTag=true&id=${this.id}&vscode-resource-origin=${encodeURIComponent(this.webviewResourceEndpoint)}`;
 	}
 
 	protected createElement(options: WebviewOptions) {