• --keyofStringsOnly added in Support number and symbol named properties with keyof and mapped types #23592
• --declarationMap from Declaration maps and transparent goto definition using them #22658
• --resolveJsonModule from Resolve the modue names with "modulename.json" to json files when doing node module resolution #22167
• New lib file added in add lib.es2018.intl + fix lib.es2017.intl #23785

See checklist for work needed: https://github.com/Microsoft/TypeScript/wiki/Release-Activities#new-compiler-option-added