Composition policy takes child instance

The composition policy now takes a child instance instead
of the child type, as in all cases we have access to the child
object.

This allows new-style objects to be contained by old-style objects.

Updated all composition policies to use standardized argument names
instead of `context` and `candidate`; this makes it easier to
understand.

Updated AddActionProvider to hardcode the object types supported.

platform/containment/bundle.js

@@ -40,9 +40,6 @@ define([
                 {
                     "category": "composition",
                     "implementation": CompositionPolicy,
-                    "depends": [
-                        "$injector"
-                    ],
                     "message": "Objects of this type cannot contain objects of that type."
                 },
                 {