[FIX] doc: implement delegation/inheritance in JS documenter

Else website_sale_wishlist.wishlist blows up the documenter:
``events`` is set to sAnimations.Class.events but that is not an "own
property" of sAnimation.Class, it is instead inherited from Widget.

If delegation is not implemented, the value resolves to <nothing>,
which blows up when trying to set its name to the "property name" (by
calling ``set_name``).

doc/_extensions/autojsdoc/parser/jsdoc.py

@@ -263,7 +263,8 @@ class ClassDoc(NSDoc):
         # FIXME: should ideally be a proxy namespace
         if method_name == 'prototype':
             return self
-        return super(ClassDoc, self).get_property(method_name)
+        return super(ClassDoc, self).get_property(method_name)\
+            or (self.superclass and self.superclass.get_property(method_name))
 
     @property
     def mixins(self):