Missing TypeScript Nodes (2)

Problem

See https://github.com/prettier/prettier/issues/1480#issuecomment-299230108 for up to date info There are still some nodes missing, but we're getting there :) Missing printer implementation: [x] "TSAsyncKeyword" (#1483) [x] "TSDecorator" (#1488) [x] "TSExportKeyword" (#1483) [x] "TSNamespaceFunctionDeclaration" (#1483) [x] "TSProtectedKeyword" (#1483) [x] "TSPublicKeyword" (#1483) [x] "TSHeritageClause" (#1483) [x] "TSExpressionWithTypeArguments (#1483) Missing in `typescript-ast-nodes.js`: [x] "TSParameterProperty" [x] "TSTypeParameter" There are also some nodes printed incorrectly, probably because some optional keywords aren't printed which should be easy to fix. And there are errors where we're trying to access properties on undefined, those are probably because TypeScript types are missing in `typescript-ast-nodes.js` or because we expect optional stuff to just be there. The raw output of running prettier of the TypeScript test suite can be found here (careful, it's big). If anyone wants to help with this drop a line here, so we don't duplicate the effort. see #1422 #13 #1306 /cc @azz