Description:
------------
The json_last_error() documentation lacks the JSON_ERROR_STATE_MISMATCH constant 
in the list of possible returned values.

Test script:
---------------
The error code '2' returned by a json_decode() of a malformed JSON string (Ex. '{"foo":"bar"}}' with double '}' at end) is not known by the constants shown in the documentation.

A glimpse in the source code, shows that there is another constant 'JSON_ERROR_STATE_MISMATCH' that matches the error code '2'.

Expected result:
----------------
--8<--
JSON_ERROR_NONE	No error has occurred	 
JSON_ERROR_DEPTH	The maximum stack depth has been exceeded	 
JSON_ERROR_STATE_MISMATCH	Invalid or malformed JSON
JSON_ERROR_CTRL_CHAR	Control character error, possibly incorrectly encoded	 
JSON_ERROR_SYNTAX	Syntax error	 
JSON_ERROR_UTF8	Malformed UTF-8 characters, possibly incorrectly encoded	
PHP 5.3.1
-->8--