[line-clamp] Fix DCHECK when balancing a line-clamp descendant

In https://crrev.com/c/6641006 it was decided to not allow using
`ScoreLineBreaking` with line-clamp involving ellipses that are
considered during line-breaking (i.e. the
`CSSLineClampLineBreakingEllipsis` runtime flag). This was done by
setting the `is_score_line_break_disabled_` flag in
`InlineItemsBuilderTemplate` if the block is a `line-clamp` container.

However, a DCHECK was also added to `ScoreLineBreaker` to verify that
score line breaking was indeed disabled in that case. And if the
line-clamp container is not itself balanced, but an in-flow descendant
of it is, then the score line breaking for that element will not be
disabled, and there will be a DCHECK failure.

In this patch, we solve this by bailing out of `ScoreLineBreaker` in
that case, just like we do if
`line_breaker.ShouldDisableScoreLineBreak()` returns true.

Bug: 40336192
Change-Id: Ibb03db18c1221aa0f2504b0c11891f8efdcc8395
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6727234
Commit-Queue: Andreu Botella <abotella@igalia.com>
Reviewed-by: Koji Ishii <kojii@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1485668}