src/vs/workbench/contrib/webview/browser/dynamicWebviewEditorOverlay.ts/DynamicWebviewEditorOverlay/postMessage
class DynamicWebviewEditorOverlay:	public postMessage(message: any, transfer?: readonly ArrayBuffer[]): void {
		if (this._webview.value) {
			this._webview.value.postMessage(message, transfer);
		} else {
			this._pendingMessages.add({ message, transfer });
		}
	}