Roll back the [31124] change to _HasDropDown so it can come before or after _KeyNavMixin in the inheritance chain, thus allowing Select to have a saner list of superclasses.  Fixes #17040, refs #16589 !strict.
Roll back the [31124] change to _HasDropDown so it can come before or after _KeyNavMixin in the inheritance chain, thus allowing Select to have a saner list of superclasses.  Fixes #17040, refs #16589 !strict.

git-svn-id: 674a2d6b1e32e53f607eb824547723f32280967e@31291 560b804f-0ae3-0310-86f3-f6aa0a117693

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