Cache addHoverClass as it is quite expensive (#643)

* Add cache and cache purging

Needed for https://github.com/rrweb-io/rrweb-snapshot/pull/85

* Add cache and cache purging

Needed for https://github.com/rrweb-io/rrweb-snapshot/pull/85

* Cache addHoverClass as it is quite expensive

https://github.com/rrweb-io/rrweb-snapshot/pull/85

* Make cache non-optional

* Make cache required on addHoverClass

packages/rrweb-snapshot/src/index.ts

@@ -6,7 +6,11 @@ import snapshot, {
   needMaskingText,
   IGNORED_NODE,
 } from './snapshot';
-import rebuild, { buildNodeWithSN, addHoverClass } from './rebuild';
+import rebuild, {
+  buildNodeWithSN,
+  addHoverClass,
+  createCache,
+} from './rebuild';
 export * from './types';
 export * from './utils';
 
@@ -16,6 +20,7 @@ export {
   rebuild,
   buildNodeWithSN,
   addHoverClass,
+  createCache,
   transformAttribute,
   visitSnapshot,
   cleanupSnapshot,