Prevent nesting of ContextThemeWrapper

brightness_mirror_container sets android:theme, causing the inflating
context to be wrapped in a ContextThemeWrapper every time it's
reinflated (because we used the old view context).

Instead, use the context of the parent for reinflation (same context
every time), so we only have one layer or theming.

Fixes: 200054259
Test: manual, dump heap after triggering reinflate many times
Change-Id: I0af5648bfc8b20dc53cb0a9064eb7b93d1f10941