Description:
------------
When unserializing a string like O:8:"stdClass":3:{s:5:"22387";s:1:"a";s:5:"22386";s:1:"a";s:5:"22368";s:1:"a";}, the resulting object will have integers as property names instead of strings.

This may be regression of #43614, marked fixed in CVS but that was a year ago.

Reproduce code:
---------------
<?php

// an object with some numeric keys
$keys = array( "1", "2", "3" );
foreach( $keys AS $key ) {
  $obj->{$key} = 'a';
}

var_dump( $obj );
$s = serialize( $obj );
$u = unserialize( $s );
var_dump( $u );

?>

Expected result:
----------------
object(stdClass)#1 (3) {
  ["1"]=>
  string(1) "a"
  ["2"]=>
  string(1) "a"
  ["3"]=>
  string(1) "a"
}
object(stdClass)#2 (3) {
  ["1"]=>
  string(1) "a"
  ["2"]=>
  string(1) "a"
  ["3"]=>
  string(1) "a"
}


Actual result:
--------------
object(stdClass)#1 (3) {
  ["1"]=>
  string(1) "a"
  ["2"]=>
  string(1) "a"
  ["3"]=>
  string(1) "a"
}
object(stdClass)#2 (3) {
  [1]=>
  string(1) "a"
  [2]=>
  string(1) "a"
  [3]=>
  string(1) "a"
}