OverlayView has a number of undocumented prototypes which tend to collide
with variables/prototypes of subclasses when compressed with a program such
as the Google Closure-Compiler.

Since these are undocumented, there is no way to know/avoid using these
names in derived objects.

Example:
function MyOverlay () {
   this.l = null; //Collides with undocumented function of
google.maps.OverlayView.
}
MyOverlay.prototype = new google.maps.OverlayView();