Demo illustrated `base-line` metric exposure
Demo illustrated `base-line` metric exposure

Summary:
A demo illustrated `base-line` metric exposure to layout system was added to RNTester.
And currently it shows that we don't support it at all.

https://cl.ly/1F0B0D430U3e

Reviewed By: sahrens

Differential Revision: D6957056

fbshipit-source-id: 28776300fc8e11950ac5ba1a5416f68d31d4e9fb

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