WIP: Show unsupported screen in dev tools for React version < 15.0.0

[danielhusar]

refs #16462

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[sizebot]

No significant bundle size changes to report.

Generated by 🚫 dangerJS against b86e3a5

[bvaughn]

I think the place we most likely want to do this check is here:

react/packages/react-devtools-shared/src/backend/index.js

Lines 50 to 56 in 2ce5801

	// Inject any not-yet-injected renderers (if we didn't reload-and-profile)
	if (!rendererInterface) {
	if (typeof renderer.findFiberByHostInstance === 'function') {
	rendererInterface = attach(hook, id, renderer, global);
	} else {
	rendererInterface = attachLegacy(hook, id, renderer, global);
	}

In the else branch (where we call attachLegacy) we should try to detect v14 and older (maybe using the ComponentTree check I mentioned). If we detect an unsupported version, we should:

1. send a message over the bridge so the frontend knows to show a modal
2. Not call any of the "attach" methods since they would just runtime error anyway.

[bvaughn]

I think this param name is a bit confusing. React DevTools always "support React" 😄 We just want to detect an unsupported version.

I think this probably doesn't belong as a store capability.

[bvaughn]

Similar to above comment. I don't think this belongs as a store capability, so this can be reverted 😄

[bvaughn]

I think we should use the ModalDialogContext to show a message if we detect an unsupported React version. We do a similar thing for React Native in WarnIfLegacyBackendDetected actually. Conceptually the two are kind of the same.

[danielhusar]

Thanks!
I'll take a look at attachRenderer.

[bvaughn]

Closing in favor of #16897