Correct multi-line text spacing.

Use double for offset when calculating bounding box, and don't
use ceiling, to prevent an extra row of pixels between lines in
multi-line text.

Change-Id: Ifd660e382cf8b946e23b58493c765d229d716652
Merge topic 'multiline_text_spacing' into master

1aa5a521 Correct multi-line text spacing.