shareX = T produces blank plot when plotting non-square subplots

In the code below when subplot is 4x3 with shareX = T, it produces a blank plot. If you make it 4x4 it works fine (or if you set shareX = F).

p <- plot_ly(y = ~rnorm(50), type = "box", name = "A") %>%
  add_trace(y = ~rnorm(50, 1), name = "B") %>%
  add_trace(y = ~rnorm(50, 1), name = "C") %>%
  add_trace(y = ~rnorm(50, 1), name = "D")

p <- subplot(p,p,p,p, shareY = TRUE)

p <- subplot(p,p,p, nrows=3, shareX = TRUE) %>%
  layout(showlegend = FALSE)

p

使用 issue 中的 R 範例重現空白輸出，比較啟用或停用 shareX 時的 4x3 和 4x4 subplot 版面配置。追蹤 plotly.R 使用的 subplot 與共用座標軸處理方式，然後為非方形情況新增或更新回歸測試。當 4x3 共用 X 軸範例能夠渲染出圖表而不是空白結果時，即表示完成。