message: revert an extra cleanup
diff: @@ -501,7 +501,7 @@ export function emitWebIDl(webidl: Browser.WebIdl, flavor: Flavor) {
  p = { name: p.name, type: [p.subtype!, p] }
  }
  const isOptional = !p.variadic && p.optional;
  - const pType = convertDomTypeToNullableTsType(p);
  + const pType = isOptional ? convertDomTypeToTsType(p) : convertDomTypeToNullableTsType(p);
  const variadicParams = p.variadic && pType.indexOf('|') !== -1;
  return (p.variadic ? "..." : "") +
  adjustParamName(p.name) +
  