Counts need to be strings for histogram to work

A quirk I found today: count values need to be strings in order to be counted as numbers when inside a histogram.

fruits = c("Apples","Apples","Apples","Oranges", "Bananas")
counts = c(5,10,3,10,5)

Doesn't work:

plot_ly(y=counts, 
        x=fruits, 
        histfunc='sum', 
        type = "histogram") %>% 
  layout(yaxis=list(type='linear'))

Does work:

plot_ly(y=as.character(counts), 
        x=fruits, 
        histfunc='sum', 
        type = "histogram") %>% 
  layout(yaxis=list(type='linear'))

首先复现 issue 中的两个 plot_ly 直方图示例，并将数值 counts 与 as.character(counts) 进行比较。跟踪 histfunc='sum' 的直方图处理流程，确定数值 counts 在何处受到不同处理。完成的标准是：数值 counts 无需转换为字符值即可生成相同的预期直方图。