Description:
------------
Failed to push to the empty array with the constant value zero defined in class scope.

We were able to push any value using empty square bracket to the array which has initialized in class definition.

However, if we use the php 5.4.34 - 5.4.37, 5.5.18 - 5.5.21,
the following message has returned and the php fails to push the value.
 
"Warning: Cannot add element to the array as the next element is already occupied in"


Test script:
---------------
<?php

class c1
{
  const ZERO = 0;
  const ONE = 1;
  public static $a1 = array(self::ONE => 'one');
  public static $a2 = array(self::ZERO => 'zero');
}

$v1 = c1::$a1;
$v2 = c1::$a2;

$v1[] = 1;
$v2[] = 1;

var_dump($v1);
var_dump($v2);

Expected result:
----------------
array(2) {
  [1]=>
  string(3) "one"
  [2]=>
  int(1)
}
array(2) {
  [0]=>
  string(4) "zero"
  [1]=>
  int(1)
}


Actual result:
--------------
array(2) {
  [1]=>
  string(3) "one"
  [0]=>
  int(1)
}
array(1) {
  [0]=>
  string(4) "zero"
}