Animation breaks with more than 10 line traces with no specified color

Works ok

p <- plot_ly(txhousing, x = ~month, y = ~log(sales), frame = ~year, split = ~city, color = I("red"))
add_lines(p) 

doesn't:

p <- plot_ly(txhousing, x = ~month, y = ~log(sales), frame = ~year, split = ~city)
add_lines(p) 

@rreusser I think this is a plotly.js issue -- any chance default colors aren't being supplied properly?

首先运行 issue 中的两个 plot_ly/add_lines 示例，比较使用显式颜色的情况与使用超过 10 个 city traces 且未指定颜色的情况。跟踪动画期间是否提供了默认颜色，然后验证无颜色示例能够正确进行动画，同时不改变显式颜色的行为。