Add a check in InitializeCore.js that PlatformConstants native module is present
Add a check in InitializeCore.js that PlatformConstants native module is present

Summary: In some enviroments PlatformConstants native module may not be presented in a project, which results in a call to undefined property and a RedBox

Reviewed By: javache

Differential Revision: D5960879

fbshipit-source-id: 80aecbe2f2a61cb410abd5f0dce8ba855e166991

javache/react-native,kesha-antonov/react-native,exponent/react-native,rickbeerendonk/react-native,myntra/react-native,rickbeerendonk/react-native,frantic/react-native,dikaiosune/react-native,hammerandchisel/react-native,hoangpham95/react-native,jevakallio/react-native,javache/react-native,cdlewis/react-native,hoastoolshop/react-native,javache/react-native,ptmt/react-native-macos,kesha-antonov/react-native,hammerandchisel/react-native,Bhullnatik/react-native,frantic/react-native,jevakallio/react-native,janicduplessis/react-native,cdlewis/react-native,myntra/react-native,hoastoolshop/react-native,javache/react-native,kesha-antonov/react-native,exponentjs/react-native,facebook/react-native,dikaiosune/react-native,kesha-antonov/react-native,arthuralee/react-native,exponent/react-native,hoangpham95/react-native,dikaiosune/react-native,pandiaraj44/react-native,jevakallio/react-native,jevakallio/react-native,frantic/react-native,cdlewis/react-native,hoastoolshop/react-native,arthuralee/react-native,hoastoolshop/react-native,hammerandchisel/react-native,pandiaraj44/react-native,hoangpham95/react-native,frantic/react-native,Bhullnatik/react-native,myntra/react-native,exponent/react-native,facebook/react-native,pandiaraj44/react-native,hoangpham95/react-native,exponentjs/react-native,myntra/react-native,hoangpham95/react-native,Bhullnatik/react-native,janicduplessis/react-native,hoangpham95/react-native,exponent/react-native,hammerandchisel/react-native,pandiaraj44/react-native,exponentjs/react-native,janicduplessis/react-native,myntra/react-native,dikaiosune/react-native,hoastoolshop/react-native,Bhullnatik/react-native,facebook/react-native,ptmt/react-native-macos,javache/react-native,jevakallio/react-native,cdlewis/react-native,exponent/react-native,rickbeerendonk/react-native,exponentjs/react-native,exponent/react-native,facebook/react-native,rickbeerendonk/react-native,dikaiosune/react-native,exponentjs/react-native,cdlewis/react-native,janicduplessis/react-native,facebook/react-native,hammerandchisel/react-native,janicduplessis/react-native,arthuralee/react-native,frantic/react-native,facebook/react-native,hoastoolshop/react-native,dikaiosune/react-native,arthuralee/react-native,ptmt/react-native-macos,ptmt/react-native-macos,kesha-antonov/react-native,facebook/react-native,exponent/react-native,kesha-antonov/react-native,hoangpham95/react-native,janicduplessis/react-native,rickbeerendonk/react-native,rickbeerendonk/react-native,exponentjs/react-native,hammerandchisel/react-native,janicduplessis/react-native,kesha-antonov/react-native,ptmt/react-native-macos,kesha-antonov/react-native,pandiaraj44/react-native,Bhullnatik/react-native,Bhullnatik/react-native,ptmt/react-native-macos,exponentjs/react-native,cdlewis/react-native,exponent/react-native,jevakallio/react-native,rickbeerendonk/react-native,Bhullnatik/react-native,myntra/react-native,jevakallio/react-native,dikaiosune/react-native,ptmt/react-native-macos,arthuralee/react-native,hoangpham95/react-native,Bhullnatik/react-native,myntra/react-native,facebook/react-native,jevakallio/react-native,dikaiosune/react-native,hammerandchisel/react-native,hammerandchisel/react-native,exponentjs/react-native,myntra/react-native,pandiaraj44/react-native,cdlewis/react-native,cdlewis/react-native,pandiaraj44/react-native,rickbeerendonk/react-native,facebook/react-native,ptmt/react-native-macos,kesha-antonov/react-native,myntra/react-native,janicduplessis/react-native,javache/react-native,javache/react-native,hoastoolshop/react-native,pandiaraj44/react-native,rickbeerendonk/react-native,cdlewis/react-native,javache/react-native,hoastoolshop/react-native,jevakallio/react-native,javache/react-native