Histogram doesn't auto calculate colorscale properties if they are undefined

[camdecoster]

Description

The histogram trace doesn't calculate the colorscale properties (cmin, cmax, etc.) if they are undefined (meaning they aren't provided in the config).

Steps to reproduce

• Add a log statement for the domain here: console.log({ domain })
• Run this test: npm run test-jasmine colorbar
• Note that the log statement shows a domain of NaN values
  LOG: Object{domain: [NaN, NaN, NaN, NaN, NaN, NaN]}

Notes

• This was discovered while working on Update color processing library to handle modern CSS color syntax #7523
• The current color processing library silently turns invalid CSS color specifiers into the color black, so the bug never causes an error

[camdecoster]

Closed by #7534.