Error in random spawning script

Hello gays. I make game for Android OS, but I have problem.
I have Random Spawning script, but it does not work in the case of development for android. If you develop for the Windows, then there are no errors.
It gives an error: Spawner.js(18,9/14/31): BCE0005: Unknown identifier: ‘i’

P.S.: I do not know much English, sorry.

var spawnPoints : Transform[];  // Array of spawn points to be used.
var enemyPrefabs : GameObject[]; // Array of different Enemies that are used.
var amountEnemies = 20;  // Total number of enemies to spawn.
var yieldTimeMin = 2;  // Minimum amount of time before spawning enemies randomly.
var yieldTimeMax = 5;  // Don't exceed this amount of time between spawning enemies randomly.

function Start()
{
    Spawn();
}

function Spawn() 
{ 
   for (i=0; i<amountEnemies; i++) // How many enemies to instantiate total.
   {
      yield WaitForSeconds(Random.Range(yieldTimeMin, yieldTimeMax));  // How long to wait before another enemy is instantiated.

      var obj : GameObject = enemyPrefabs[Random.Range(0, enemyPrefabs.length)]; // Randomize the different enemies to instantiate.
      var pos: Transform = spawnPoints[Random.Range(0, spawnPoints.length)];  // Randomize the spawnPoints to instantiate enemy at next.

      Instantiate(obj, pos.position, pos.rotation); 
   } 
}

try:

for (int i=0; i<amountEnemies; i++)