Remove createReactClass from LayoutEventsTest
Remove createReactClass from LayoutEventsTest

Summary:
Related to #21581

Remove createReactClass from LayoutEventsTest and refactor a little bit.

Reviewed By: TheSavior

Differential Revision: D10345794

fbshipit-source-id: 40e42f6e9afece5ddf527f91927e75cb1669b696

myntra/react-native,hammerandchisel/react-native,hammerandchisel/react-native,hoangpham95/react-native,exponentjs/react-native,exponent/react-native,arthuralee/react-native,facebook/react-native,hoangpham95/react-native,myntra/react-native,javache/react-native,exponent/react-native,arthuralee/react-native,facebook/react-native,janicduplessis/react-native,exponentjs/react-native,javache/react-native,javache/react-native,pandiaraj44/react-native,exponent/react-native,janicduplessis/react-native,hoangpham95/react-native,hammerandchisel/react-native,javache/react-native,myntra/react-native,janicduplessis/react-native,myntra/react-native,facebook/react-native,exponent/react-native,pandiaraj44/react-native,arthuralee/react-native,hoangpham95/react-native,janicduplessis/react-native,hoangpham95/react-native,arthuralee/react-native,exponent/react-native,exponent/react-native,janicduplessis/react-native,javache/react-native,pandiaraj44/react-native,exponentjs/react-native,javache/react-native,hoangpham95/react-native,myntra/react-native,pandiaraj44/react-native,facebook/react-native,hoangpham95/react-native,facebook/react-native,myntra/react-native,pandiaraj44/react-native,pandiaraj44/react-native,pandiaraj44/react-native,arthuralee/react-native,exponentjs/react-native,exponent/react-native,janicduplessis/react-native,facebook/react-native,janicduplessis/react-native,facebook/react-native,pandiaraj44/react-native,javache/react-native,myntra/react-native,facebook/react-native,javache/react-native,hammerandchisel/react-native,exponentjs/react-native,myntra/react-native,hammerandchisel/react-native,exponent/react-native,exponentjs/react-native,hammerandchisel/react-native,janicduplessis/react-native,myntra/react-native,hoangpham95/react-native,hammerandchisel/react-native,javache/react-native,exponentjs/react-native,hammerandchisel/react-native,facebook/react-native,exponentjs/react-native