Cleanup of SkyBinding, and resultant yak shaving.

sky/sdk/lib/types/node.dart

 class AbstractNode {
 
   // AbstractNode represents a node in a tree.
   // The AbstractNode protocol is as follows:
   // - When a subclass is changing the parent of a child, it should
   //   call either parent.adoptChild(child) or parent.dropChild(child)
   //   as appropriate. Subclasses should expose an API for
   //   manipulating the tree if you want to (e.g. a setter for a
   //   'child' property, or an 'add()' method to manipulate a list).
   // - You can see the current parent by querying 'parent'.
@@ skipping 62 matching lines @@
   void dropChild(AbstractNode child) { // only for use by subclasses
     assert(child != null);
     assert(child._parent == this);
     assert(child.attached == attached);
     child._parent = null;
     if (attached)
       child.detach();
   }
 
 }