[patch] [ccla] Grid: shift+F10 no longer invokes grid context menu (breaks keyboard a11y)

[Becky Gibson]

open dojox/grid/tests/test_grid_column_display.html. Navigate to a grid header using the keyboard, with focus on a grid column header cell, press shift+F10 - a grid specific context menu should be displayed but the default browser context menu is displayed.

This is related to #9756 because focus is no longer on the actual grid column header cell. Need to modify code so grid listens for oncontext event rather than view.

[Becky Gibson]

Attached a patch that modifies the node that the contextMenu is bound to when the grid header gets focus. If grid header gets keyboard focus, the contextMenu is bound to the grid.domNode because that controls the focus and keyevents for the header cells. When the header loses focus, the contextMenu is bound to the grid.viewsHeaderNode so clicking the right mouse button with the mouse over a header cell will invoke the context menu. Also did some cleanup to remove duplicate code when the header loses focus. During this fix I uncovered #10515 which existed before this fix and still exists.

[Becky Gibson]

updated test files to check that shift+F10 opens header context menu

[Becky Gibson]

(In [21075]) fixes #10483 Since actual focus no longer goes to grid header cells, have to bind/unbind the contextMenu to the grid.domNode or grid.viewsHeaderNode as the header cells become active. Updated a11y tests for invoking contextMenu on header

[Becky Gibson]

(In [21076]) refs #10483 - check in fix to trunk as well as Dojo 1.4.x branch