call toString on fontWeight else throws error if passed an integer
call toString on fontWeight else throws error if passed an integer

Summary:
expects a string, throws error NSNumber cannot be converted to NSString if passed an integer, added toString() method to allow integers, and keep consistency, fontSize allows int.
Closes https://github.com/facebook/react-native/pull/10483

Differential Revision: D5128581

Pulled By: shergin

fbshipit-source-id: 21b1ddd35210c8f061506d71b936cc0ff490d999

facebook/react-native,mironiasty/react-native,tszajna0/react-native,skevy/react-native,formatlos/react-native,facebook/react-native,PlexChat/react-native,ptmt/react-native-macos,exponentjs/react-native,forcedotcom/react-native,cdlewis/react-native,janicduplessis/react-native,rickbeerendonk/react-native,exponentjs/react-native,doochik/react-native,hoangpham95/react-native,javache/react-native,javache/react-native,Bhullnatik/react-native,cpunion/react-native,cpunion/react-native,formatlos/react-native,mironiasty/react-native,javache/react-native,forcedotcom/react-native,javache/react-native,exponent/react-native,arthuralee/react-native,frantic/react-native,makadaw/react-native,thotegowda/react-native,cdlewis/react-native,Guardiannw/react-native,jevakallio/react-native,cpunion/react-native,dikaiosune/react-native,aljs/react-native,dikaiosune/react-native,facebook/react-native,forcedotcom/react-native,shrutic123/react-native,hoastoolshop/react-native,aljs/react-native,peterp/react-native,PlexChat/react-native,Bhullnatik/react-native,jasonnoahchoi/react-native,kesha-antonov/react-native,hammerandchisel/react-native,skevy/react-native,doochik/react-native,Livyli/react-native,Bhullnatik/react-native,Livyli/react-native,negativetwelve/react-native,brentvatne/react-native,jasonnoahchoi/react-native,ptmt/react-native-macos,hoangpham95/react-native,myntra/react-native,brentvatne/react-native,forcedotcom/react-native,pandiaraj44/react-native,hoangpham95/react-native,ptmt/react-native-macos,Livyli/react-native,aljs/react-native,peterp/react-native,farazs/react-native,kesha-antonov/react-native,janicduplessis/react-native,myntra/react-native,mironiasty/react-native,jevakallio/react-native,thotegowda/react-native,hoangpham95/react-native,tszajna0/react-native,exponentjs/react-native,Livyli/react-native,shrutic123/react-native,farazs/react-native,farazs/react-native,facebook/react-native,formatlos/react-native,rickbeerendonk/react-native,mironiasty/react-native,janicduplessis/react-native,thotegowda/react-native,Ehesp/react-native,PlexChat/react-native,javache/react-native,janicduplessis/react-native,rickbeerendonk/react-native,peterp/react-native,hoastoolshop/react-native,shrutic123/react-native,pandiaraj44/react-native,peterp/react-native,makadaw/react-native,makadaw/react-native,dikaiosune/react-native,gilesvangruisen/react-native,aljs/react-native,mironiasty/react-native,brentvatne/react-native,exponent/react-native,aljs/react-native,Ehesp/react-native,tszajna0/react-native,makadaw/react-native,Guardiannw/react-native,exponent/react-native,formatlos/react-native,tszajna0/react-native,janicduplessis/react-native,Bhullnatik/react-native,facebook/react-native,exponent/react-native,gilesvangruisen/react-native,cdlewis/react-native,aljs/react-native,ptmt/react-native-macos,pandiaraj44/react-native,jasonnoahchoi/react-native,Guardiannw/react-native,farazs/react-native,gilesvangruisen/react-native,Bhullnatik/react-native,peterp/react-native,myntra/react-native,PlexChat/react-native,facebook/react-native,ptmt/react-native-macos,cpunion/react-native,hammerandchisel/react-native,arthuralee/react-native,javache/react-native,pandiaraj44/react-native,PlexChat/react-native,Guardiannw/react-native,farazs/react-native,kesha-antonov/react-native,jevakallio/react-native,dikaiosune/react-native,farazs/react-native,jasonnoahchoi/react-native,jasonnoahchoi/react-native,skevy/react-native,forcedotcom/react-native,forcedotcom/react-native,aljs/react-native,myntra/react-native,Guardiannw/react-native,Ehesp/react-native,arthuralee/react-native,hoastoolshop/react-native,frantic/react-native,kesha-antonov/react-native,myntra/react-native,Ehesp/react-native,ptmt/react-native-macos,pandiaraj44/react-native,thotegowda/react-native,Ehesp/react-native,rickbeerendonk/react-native,rickbeerendonk/react-native,cdlewis/react-native,jasonnoahchoi/react-native,makadaw/react-native,doochik/react-native,skevy/react-native,mironiasty/react-native,jevakallio/react-native,kesha-antonov/react-native,doochik/react-native,jevakallio/react-native,myntra/react-native,farazs/react-native,ptmt/react-native-macos,jasonnoahchoi/react-native,rickbeerendonk/react-native,hoangpham95/react-native,frantic/react-native,cdlewis/react-native,myntra/react-native,javache/react-native,shrutic123/react-native,gilesvangruisen/react-native,Guardiannw/react-native,exponentjs/react-native,formatlos/react-native,skevy/react-native,pandiaraj44/react-native,ptmt/react-native-macos,brentvatne/react-native,hoastoolshop/react-native,hoastoolshop/react-native,negativetwelve/react-native,hammerandchisel/react-native,gilesvangruisen/react-native,shrutic123/react-native,farazs/react-native,Bhullnatik/react-native,negativetwelve/react-native,exponentjs/react-native,formatlos/react-native,brentvatne/react-native,doochik/react-native,frantic/react-native,Livyli/react-native,dikaiosune/react-native,Livyli/react-native,doochik/react-native,hoangpham95/react-native,aljs/react-native,doochik/react-nativ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