title: Add a JavaScript getter/setter to a native unconfigurable property
body: <p>I am using special getter/setters to intercept changes made to properties of an object, and it currently works great for any normal user-defined properties. However, I would <em>love</em> if I could employ the same idea to built-in properties like <code>HTMLInputElement.value</code> or <code>Array.length</code>, but these are unfortunately defined as unconfigurable and thus I get an error when attempting to redefine them using a getter/setter.</p>
  
  <p>I'm just wondering if there's any kind of (reliable) hack that I can do to force these to be redefined without breaking their internal operation.</p>
  
  <p>If not, I'll probably be forced to define alternate properties for all of these that simply map to the native properties and use them instead, but that's just so not ideal.</p>