Some general cleanup of _KeyNavContainer.     Also modifying Menu to not access this.focusedChild when the !MenuItem of interest is already in a local variable.   Refs #16323 !strict.
Some general cleanup of _KeyNavContainer.     Also modifying Menu to not access this.focusedChild when the !MenuItem of interest is already in a local variable.   Refs #16323 !strict.

git-svn-id: 674a2d6b1e32e53f607eb824547723f32280967e@29979 560b804f-0ae3-0310-86f3-f6aa0a117693

harbalk/delite,Sam-Cummins/delite,Sam-Cummins/delite,kitsonk/delite,harbalk/delite,kitsonk/delite