Problem with autoscrolling with Milk v2 style

[lsieradzki]

The issue was described here: https://www.phpbb.com/customise/db/extension/mchat_extension/support/topic/185161
The fix was initially applied but then there were some changes in the code and the regression was introduced. Here is what needs to be changed now:

From:

var height = this.container.height();
if (scrollHeight - height - scrollTop <= scrollLeeway) {
  this.container.scrollTop(scrollHeight);
}

To:

var height = this.container.innerHeight();
if (scrollHeight - height - scrollTop <= scrollLeeway) {
  this.container.scrollTop(scrollHeight);
}