Fix an incorrect display position of error popup in RTL layout

Symptom:
The display position of error popup is incorrect in RTL layout such as
Arabic language.

Root cause:
In LTR layout, a popup window is anchored to the bottom-left corner of
the anchor view. But in RTL layout, it's anchored to the bottom-right.
showError calculates a position for RTL by itself and it gets a wrong
result.

Solution:
Set the base alignment of the error popup to the bottom-left even though
it's in RTL.

Bug: 69402857
Change-Id: Iae099984e6c47feca078658ddc44ab905995fe0d