Fabric: RCTSurfaceRegistry now stores Surfaces as weak references
Fabric: RCTSurfaceRegistry now stores Surfaces as weak references

Summary:
@public
RCTSurfaceRegistry always promised this in the documentation but never actually did.

Reviewed By: sahrens

Differential Revision: D9652732

fbshipit-source-id: f3d06b95192e024273dc0e3a1c2753ca92370338

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