Preview functionality does not work when file with `preview` call isn't included in the bundle

[filip131311]

Preview functionality works only when the preview(<Component/>) is called from the file that is imported as a part of the application. Otherwise "open preview" button still appears on top of it but does not work due to component not being registered in AppRegistry.

examples: not imported:

imported:

Additional context: Currently the preview function is defined in lib/preview.js file and is injected into aplication node_modules by lib/babel_transformer.js file. When you click "open preview" the function that is most important is defined in lib/warpper.js and is called openPreview.

[jakub-gonet]

To repro:

• create component in a different file than main entry point and import it
• try using preview in the component file directly

alternative: remove component import and try to to do it directly in the file – it won't be bundled with the app.