Implement the StockSpanner class to compute the span of the stock's price for each day. The span on a given day is the number of consecutive days (ending today, going backwards) for which the price was less than or equal to today's price.

Example: For daily prices [100, 80, 60, 70, 60, 75, 85], the spans are [1, 1, 1, 2, 1, 4, 6].