src/vs/platform/webview/electron-main/webviewMainService.ts/WebviewMainService/getFrameByName
class WebviewMainService:	private getFrameByName(windowId: WebviewWindowId, frameName: string): WebFrameMain {
		const window = this.windowsMainService.getWindowById(windowId.windowId);
		if (!window?.win) {
			throw new Error(`Invalid windowId: ${windowId}`);
		}
		const frame = window.win.webContents.mainFrame.framesInSubtree.find(frame => {
			return frame.name === frameName;
		});
		if (!frame) {
			throw new Error(`Unknown frame: ${frameName}`);
		}
		return frame;
	}