Show better error message when accessing React APIs on React Native

[satya164]

Motivation:

Lots of examples on the web still have the old way to import React APIs from React Native. Also when someone upgrades to latest version of React Native without reading the release notes can get confused. This PR adds getters for createClass and Component and throws an error with a better error message when they are accessed.

Test plan:

Trying to use ReactNative.createClass or ReactNative.Component will throw an error with this error message.

There's currently a bug in symbolicateStackTrace which actually crashes the app after showing the error due to the stack being null when updating the stack trace. But that's a separate issue which should be fixed separately. For now, to prevent the crash, we need to add the following before the return statement here - https://github.com/facebook/react-native/blob/master/Libraries/JavaScriptAppEngine/Initialization/symbolicateStackTrace.js#L29,

if (json.error) {
  throw new Error(json.error);
}

There's still the issue of stack being null, which prevents us from showing a proper stack trace.

Related #7722

cc @mkonicek

[ghost]

By analyzing the blame information on this pull request, we identified @sebmarkbage and @nicklockwood to be potential reviewers.

[eslint-bot]

parameter key Missing annotation

[satya164]

I'll fix the flow error soon.

[javache]

Is it possible to make these __DEV__ only? (preferably the whole definition, otherwise just the method contents).

[satya164]

@javache thanks. will make the method contents __DEV__ only. I don't think I can do that for the whole block.

[satya164]

@javache updated :)

[javache]

@facebook-github-bot shipit

[ghost]

Thanks for importing. If you are an FB employee go to Phabricator to review.