add keepIframeSrcFn option (#81)

* add allowIframe option to snapshot

* rename allowIframe to keepIframeSrcFn

typings/snapshot.d.ts

@@ -1,4 +1,4 @@
-import { serializedNodeWithId, INode, idNodeMap, MaskInputOptions, SlimDOMOptions, MaskTextFn } from './types';
+import { serializedNodeWithId, INode, idNodeMap, MaskInputOptions, SlimDOMOptions, MaskTextFn, KeepIframeSrcFn } from './types';
 export declare const IGNORED_NODE = -2;
 export declare function absoluteToStylesheet(cssText: string | null, href: string): string;
 export declare function absoluteToDoc(doc: Document, attributeValue: string): string;
@@ -17,6 +17,7 @@ export declare function serializeNodeWithId(n: Node | INode, options: {
     maskInputOptions?: MaskInputOptions;
     maskTextFn: MaskTextFn | undefined;
     slimDOMOptions: SlimDOMOptions;
+    keepIframeSrcFn?: KeepIframeSrcFn;
     recordCanvas?: boolean;
     preserveWhiteSpace?: boolean;
     onSerialize?: (n: INode) => unknown;
@@ -37,6 +38,7 @@ declare function snapshot(n: Document, options?: {
     onSerialize?: (n: INode) => unknown;
     onIframeLoad?: (iframeINode: INode, node: serializedNodeWithId) => unknown;
     iframeLoadTimeout?: number;
+    keepIframeSrcFn?: KeepIframeSrcFn;
 }): [serializedNodeWithId | null, idNodeMap];
 export declare function visitSnapshot(node: serializedNodeWithId, onVisit: (node: serializedNodeWithId) => unknown): void;
 export declare function cleanupSnapshot(): void;

typings/types.d.ts

@@ -88,3 +88,4 @@ export declare type SlimDOMOptions = Partial<{
     headMetaVerification: boolean;
 }>;
 export declare type MaskTextFn = (text: string) => string;
+export declare type KeepIframeSrcFn = (src: string) => boolean;