title: Cannot assign to 'Boolean' because it is a constant or a read-only property
body: <p>I am creating a typescript object to represent read/write permissions in my app, but I came across this quirk in assigning the variables that makes no sense to me.  Hopefully, someone can look at this and tell me what I am doing wrong.  </p>
  
  <pre><code>export class Permission {
         watcher:Object =  { read:Boolean = true};
  }
  </code></pre>
  
  <p>The previous code results in a error which says:</p>
  
  <p>[ts] Cannot assign to 'Boolean' because it is a constant or a read-only property.
  const Boolean: BooleanConstructor</p>
  
  <p>I'm probably just doing something stupid, so apologies in advance if this is super newbish.</p>