Update text rendering delegates.

The flags for RTL and LTR are simplified in commit
0a1d91862a3822dcbbb412bcd6d69b0f5f079f8b. This change follows up the
same in LayoutLib.

This also fixes the following bug which incorrectly computed runs with
'en-dash' (\u20132) as RTL.

Bug: http://b.android.com/69432
Change-Id: Iaed62d13ce31f107773576ed2ef412be6037cd04