Fix FloatingToolbar positioning for RTL.

-The position of the toolbar was forced to the left side in an attempt
to fix an RTL bug. This led to wrong positioning in LTR.
This is now fixed by using a dynamic "show" animation that takes into
consideration already set positions.

-The correct position of the toolbar wasn't recalculated on updates
for RTL. This is now fixed.

Bug:21455067
Change-Id: I0b31a8fd3c95549f5f10133a47a4d3ef27689010