src/vs/workbench/contrib/webview/browser/webviewService.ts/WebviewService/createWebviewOverlay
class WebviewService:	createWebviewOverlay(initInfo: WebviewInitInfo): IOverlayWebview {
		const webview = this._instantiationService.createInstance(OverlayWebview, initInfo);
		this.registerNewWebview(webview);
		return webview;
	}