in src/scanner.ts [325:340]
public isStrictModeReservedWord(id: string): boolean {
switch (id) {
case 'implements':
case 'interface':
case 'package':
case 'private':
case 'protected':
case 'public':
case 'static':
case 'yield':
case 'let':
return true;
default:
return false;
}
}