Respect grapheme clusters in Layout#getOffsetForHorizontal.

TextUtils#getOffsetAfter was used for getting the next
offset in Layout#getOffsetForHorizontal. However, this
method doesn't treat grapheme clusters properly.
Changed to use TextLine#getOffsetToLeftRightOf instead of
TextUtils#getOffsetAfter.

Bug: 25375561
Change-Id: I96c9e6e5da65adfb5266446ecab852c52628dbb5
1 file changed