Modularize master branch.

_mapCacheClear.js

@@ -0,0 +1,21 @@
+import Hash from './_Hash.js';
+import ListCache from './_ListCache.js';
+import Map from './_Map.js';
+
+/**
+ * Removes all key-value entries from the map.
+ *
+ * @private
+ * @name clear
+ * @memberOf MapCache
+ */
+function mapCacheClear() {
+  this.size = 0;
+  this.__data__ = {
+    'hash': new Hash,
+    'map': new (Map || ListCache),
+    'string': new Hash
+  };
+}
+
+export default mapCacheClear;