_bucketRemoveBody = function(grid, bucket, body) {
        // remove from bucket
        bucket.splice(Common.indexOf(bucket, body), 1);

        // update pair counts
        for (var i = 0; i < bucket.length; i++) {
            // keep track of the number of buckets the pair exists in
            // important for _createActivePairsList to work
            var bodyB = bucket[i],
                pairId = Pair.id(body, bodyB),
                pair = grid.pairs[pairId];

            if (pair)
                pair[2] -= 1;
        }
    }
Removes a body from a bucket.
@method _bucketRemoveBody
@private
@param {} grid
@param {} bucket
@param {} body