Description:
------------
negative assertions doesn't work with long text (~60000bytes) as expected

Reproduce code:
---------------
function test($str, $cnt) {
	$str = 'test "123'.str_repeat($str,$cnt).'456"';
	return preg_match('#".*?(?<!\\\\)"#', $str);
}
var_dump(test('\"', 20000)); //40K
var_dump(test('\"', 30000)); //60K <--
var_dump(test('"', 100000)); //100K

Expected result:
----------------
X-Powered-By: PHP/4.4.4
Content-type: text/html

int(1)
int(1) <--
int(1)


Actual result:
--------------
X-Powered-By: PHP/5.2.0 ( and PHP/5.2.2)
Content-type: text/html

int(1)
int(0) <--
int(1)