nested record iframe (#63)

* pick nested branch

* iframe snapshot

* temp: add bundle file to git

* revert ignore file

* refactor iframe impl
1. do callback one iframe is loaded, let rrweb handle the rest
2. handle iframe as normal element in rebuild

* rename hook function

typings/rebuild.d.ts

@@ -5,10 +5,12 @@ export declare function buildNodeWithSN(n: serializedNodeWithId, options: {
     map: idNodeMap;
     skipChild?: boolean;
     hackCss: boolean;
+    afterAppend?: (n: INode) => unknown;
 }): INode | null;
 declare function rebuild(n: serializedNodeWithId, options: {
     doc: Document;
     onVisit?: (node: INode) => unknown;
     hackCss?: boolean;
+    afterAppend?: (n: INode) => unknown;
 }): [Node | null, idNodeMap];
 export default rebuild;