Description:
------------
json_encode/decode uses 'precision'.
It should use 'serialize.precision' to handle float like JSON numeric to be more precise.


Test script:
---------------
[yohgaki@dev PHP-master]$  php -r '$v = 10/3; var_dump(json_encode($v));'
string(15) "3.3333333333333"

[yohgaki@dev PHP-master]$  php -r '$v = 10/3; ini_set("precision", 17);var_dump(json_encode($v));'
string(18) "3.3333333333333335"

[yohgaki@dev PHP-master]$ php
<?php
var_dump(json_decode('{ "v" : 0.12345678901234567890 }'));
ini_set('precision', 17);
var_dump(json_decode('{ "v" : 0.12345678901234567890 }'));
?>

object(stdClass)#1 (1) {
  ["v"]=>
  float(0.12345678901235)
}
object(stdClass)#1 (1) {
  ["v"]=>
  float(0.12345678901234568)
}