Fix typo in built-in class docs.

 * Returns an array of all properties (enumerable or not) found

 * directly upon a given object.

 *

 * Rreturns an array whose elements are strings corresponding to the

 * Returns an array whose elements are strings corresponding to the

 * enumerable and non-enumerable properties found directly upon

 * obj. The ordering of the enumerable properties in the array is

 * consistent with the ordering exposed by a for...in loop (or by