noflip left: 0; rule for overlays

We were accidentally positioning overlays right: 0; in RTL
because of a missing noflip rule, which wrecks havoc
with absolute positioning of things in these overlays.

Fixing this allows us to remove special positioning code
for RTL in TextInputMenuWidget.

Change-Id: I4c0cefd0096debfc870ca0fe5692ad0e1555beb1
Merge "noflip left: 0; rule for overlays"