Fix PropType of Formatted{,HTML}Message to accept any component

[wereHamster]

A React component is not the same as a React element! In our case, the tagName prop can be anything that can be passed to React.createElement(). Unfortunately the prop-types package doesn't provide a suitable validation function, so people are forced to build their own.

See facebook/prop-types#200 for a related discussion.

[yahoocla]

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[wereHamster]

@yahoocla please check again.

[redonkulus]

ljharb mentions in that issue:

"it has a render function" is a pretty brittle check, when react-is has a robust isForwardRef method available.

Should we try to leverage react-is as well?

[wereHamster]

I didn't want to add another dependency. Ideally prop-types would provide that validation itself, once it does you can switch to it. Until that time, this is a net improvement IMO.

[papasmile]

There is a PR out for adding 'component' to prop-types and it relies on react-is. I think copying some of what was done there would be better than a workaround: facebook/prop-types#211

[wereHamster]

Alright, I'll close this and wait until the prop-types package provides the validation. In the meantime, I'll be using this to silence the warning (I rely on TypeScript anyway):

if (process.env.NODE_ENV !== "production") {
  require("react-intl").FormattedMessage.propTypes.tagName = require("prop-types").any;
}