Prevent background overflowing TimeText

Currently TimedText sometimes uses a bigger font-size but not a bigger
line-height. This sometimes causes TimedText's background to clash with
the text resulting in horizontally cut-off texts.

This issue will be resolved with this patch.

Bug: 54901
Change-Id: I97d3e6aa187f2e88d2648d26d93eed68a5751b87
Merge "Prevent background overflowing TimeText"