Fix violation in DecorContext

The issue happens when activity is launched on the secondary
display. It's because the base context of DecorContext is
a DisplayContext, but we should check #isConfigurationContext in
associatd window's Context instead, like DecorContext#isUiContext

fixes: 242571036
Test: manual - launch activity on the secondary display

Merged-In: Ie2659fb31248ad64099018bfebb6a6b43c72f466
Change-Id: Ie2659fb31248ad64099018bfebb6a6b43c72f466