Revert "RecentsPanelView: remove internal getter for isHighEndGfx()"

This reverts commit 64d12b8cc8a1016d3a28777b532fcf1b441ed42d.
Revert "Memoize memory class lookup methods"

This reverts commit ad267fd9ffa08697a530fab446c1c68cb5e34ba7.
Revert "ActivityManager: Rejigger HighEndGfx: only propget/stringcomp and resget once (in isHighEnd, rather than constructor)"

This reverts commit d4e07a0c727dabfae636c47d980544d0033941eb.