Attribute mapping should work for template decorators

[jbdeboer]

e.g., I have a decorator:

@Decorator(
    children: Directive.TRANSCLUDE_CHILDREN,
    selector:'transcluded-foo',
    map: const {
      'is-present': '@isPresent'
    })
class FooDecorator {

  bool isPresent => some computation
}

However, since the decorator is transcluded, the attributes are never bound. There is no technical reason for this limitation.

[naomiblack]

@vsavkin can you take a look into this with @jbdeboer and assess effort to fix?