Make NaivePersistentMap serializable.
package com.google.javascript.jscomp.newtypes;
+import java.io.Serializable;
import java.util.HashMap;
import java.util.Map;
import java.util.Set;
/** A naive persistent map that does too many copies */
-final class NaivePersistentMap<K, V> extends PersistentMap<K, V> {
+final class NaivePersistentMap<K, V> extends PersistentMap<K, V> implements Serializable {
private final Map<K, V> map;
private NaivePersistentMap(Map<K, V> m) {
