Description:
------------
var_export() does escape arraykeys properly, but doesn't use the same code for escaping properties. This might lead to code injections (when user-input can be used for a propery name and the var_export()ed code is eval()ed).

This was fixed for arraykeys in #19929 and #25758

Test script:
---------------
<?php
  $x = new stdClass();
  $x->{'\' => 5)); echo "Hack.\n"; array(array(\''} = 5;
  var_export($x);
?>

Expected result:
----------------
stdClass::__set_state(array(
   '\' => 5)); echo "Hack.\n"; array(array(\'' => 5,
))

Note the backslashes.

Actual result:
--------------
stdClass::__set_state(array(
   '' => 5)); echo "Hack.\n"; array(array('' => 5,
))