Bump to v4.7.0.

size.js

@@ -1,14 +1,21 @@
+import getTag from './_getTag';
 import isArrayLike from './isArrayLike';
+import isObjectLike from './isObjectLike';
 import isString from './isString';
 import keys from './keys';
 import stringSize from './_stringSize';
 
+/** `Object#toString` result references. */
+var mapTag = '[object Map]',
+    setTag = '[object Set]';
+
 /**
  * Gets the size of `collection` by returning its length for array-like
- * values or the number of own enumerable properties for objects.
+ * values or the number of own enumerable string keyed properties for objects.
  *
  * @static
  * @memberOf _
+ * @since 0.1.0
  * @category Collection
  * @param {Array|Object} collection The collection to inspect.
  * @returns {number} Returns the collection size.
@@ -31,6 +38,12 @@ function size(collection) {
     var result = collection.length;
     return (result && isString(collection)) ? stringSize(collection) : result;
   }
+  if (isObjectLike(collection)) {
+    var tag = getTag(collection);
+    if (tag == mapTag || tag == setTag) {
+      return collection.size;
+    }
+  }
   return keys(collection).length;
 }