function removeItems(arr, startIdx, removeCount) {
    var length = arr.length;
    var i;
    if (startIdx >= length || removeCount === 0) {
        return;
    }
    removeCount = (startIdx + removeCount > length ? length - startIdx : removeCount);
    var len = length - removeCount;
    for (i = startIdx; i < len; ++i) {
        arr[i] = arr[i + removeCount];
    }
    arr.length = len;
}
Remove items from a javascript array without generating garbage
@function removeItems
@memberof PIXI.utils
@param {Array<any>} arr - Array to remove elements from
@param {number} startIdx - starting index
@param {number} removeCount - how many to remove