Add toObject to _.pairs.

lodash.src.js

@@ -10000,6 +10000,8 @@
      * // => [['barney', 36], ['fred', 40]] (iteration order is not guaranteed)
      */
     function pairs(object) {
+      object = toObject(object);
+
       var index = -1,
           props = keys(object),
           length = props.length,