Use array spread to push multiple items to labelColors

[RobbieTheWagner]

I believe this should allow for arrays to be returned from labelColor. I have not tested it yet, but I am going to now.

[benmccann]

I believe the spread operator does not work in IE11, which is a browser we support

[benmccann]

Thanks for the PR. For now, I'm going to close this since it's failing the tests and incompatible with IE. Please feel free to reopen when those issues are addressed

[RobbieTheWagner]

@benmccann do you guys not use babel?

[benmccann]

No, we don't

[RobbieTheWagner]

@benmccann any particular reason to not use it?

[benmccann]

See #5787 (comment)

[RobbieTheWagner]

@benmccann why not use Babel and just transpile to the targets you want? That comment seems to be concerned about browser support, which is totally doable with Babel.

I really need to be able to specify multiple label colors. I can return an array from the label callback, which gives me two labels in the tooltip, but then I have no way to specify different colors for them. I tried custom tooltips, but they never show up at all, not sure why.

[benmccann]

See #6555 for discussion on babel