Widget: Add document and window properties

[Scott González]

Widgets frequently need to reference the document and/or window. However, the references are usually done with the document and window globals which breaks cross-window widgets. Adding properties that reference the document and window would make it much easier to build widgets properly.

[Scott González]

Widget: Added window and document properties. Fixes #7801 - Widget: Add document and window properties.

Changeset: a0856efef3c392d413aa6cd9bd084dc601a337c6

[Aziz Gazanchiyan]

We still miss these options for many of other widgets. The one I really miss is Datepicker - it is totally bound to top document/window, making it impossible to use in iframes.

[rdworth]

Datepicker is unique in that it is the only one of all the interactions and all the widgets that does not use the widget factory, so it's not able to take advantage of a fix/feature like this. This will be handled in the Datepicker rewrite.