Fabric: Using `traitCast` in Differentiator
Fabric: Using `traitCast` in Differentiator

Summary:
The Diffing is one of the hottest pieces of Fabric. Removing dynamic_cast here should improve perf. See the previous diff for more details.

Changelog: [Internal] Fabric-specific internal change.

Reviewed By: sammy-SC

Differential Revision: D20052030

fbshipit-source-id: 27fd9f34f2a1f9d22b9da6b1e3c1a2982045c07a

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