Base64.Encode performance improvements
Base64.Encode performance improvements

KrzysztofCwalina/corefxlab,Vedin/corefxlab,VSadov/corefxlab,benaadams/corefxlab,VSadov/corefxlab,adamsitnik/corefxlab,adamsitnik/corefxlab,VSadov/corefxlab,whoisj/corefxlab,KrzysztofCwalina/corefxlab,Vedin/corefxlab,joshfree/corefxlab,ericstj/corefxlab,Vedin/corefxlab,benaadams/corefxlab,ericstj/corefxlab,stephentoub/corefxlab,whoisj/corefxlab,VSadov/corefxlab,Vedin/corefxlab,stephentoub/corefxlab,ahsonkhan/corefxlab,hanblee/corefxlab,VSadov/corefxlab,stephentoub/corefxlab,joshfree/corefxlab,alexperovich/corefxlab,tarekgh/corefxlab,Vedin/corefxlab,weshaggard/corefxlab,Vedin/corefxlab,stephentoub/corefxlab,dotnet/corefxlab,stephentoub/corefxlab,VSadov/corefxlab,ericstj/corefxlab,stephentoub/corefxlab,ericstj/corefxlab,tarekgh/corefxlab,ahsonkhan/corefxlab,ericstj/corefxlab,ericstj/corefxlab,hanblee/corefxlab,dotnet/corefxlab