scope as Map constructors do not respect default "@" values

[justinbmeyer]

If you define a Map view model like:

var PanelViewModel = can.Map.extend({
  title: "@"
})

And specify it as scope on a can.Component like:

can.Component.extend({
  tag: "panel"
  scope: PanelViewModel
})

The title value is not read from the <panel> element's attribute.

<panel title="Libraries">Content</panel>

$("panel").scope().attr("title") //-> "@", but should be "Libraries".

[andykant]

(Fixed with the pull request)