Isolate focus color filter

The mask color filter has an alpha applied to it, it should not be used
on the focused states.

Focus works differently, where the alpha is defined by the state itself
(20% for hover, and 60% focus,) combined with the paint alpha.

Test: adb shell input keyevent 22
Test: manual on list item (not masked)
Test: manual on button (masked)
Fixes: 184717563
Change-Id: I01b8540face638330d016b413e70f2b74ce5592c