CEA-608 specifies a "safe-area" in which the captions should be rendered. This change adjusts all of the cue positions so they are within that safe area. It also fixes a minor issue in which roll up captions would drift towards the last row if a preamble address code had the "next row toggle" bit set.
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Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=141077433
