[LFC][IFC] Keep the LineBreaker object around until after the line is closed.

[zalan]

This is in preparation for being able to point to an earlier wrapping opportunity.

[Radar WebKit Bug Importer]

<rdar://problem/58222870>

[zalan]

        In order to be able to point back to an earlier line wrap opportunity on the line e.g.
        <div style="white-space: pre"><span style="white-space: normal">earlier_wrap opportunities</span> <span>can't_wrap_this content</span></div>
        the LineBreaker class needs more context.
        Currently (taking the example above), if the available space runs out somewhere around the second <span> we would just simply
        overflow the line since the overflowing content has a style saying "do not wrap".
        However the line has multiple earlier wrap opportunities inside the first <span>.
        Since we construct a LineBreaker object for each continuous run 

        1. [container start][earlier_wrap]
        2. [ ]
        3. [opportunities][container end]
        4. [ ]
        5. [container start][can't_wrap_this]
        6. [ ]
        7. [content][container end]

        the LineBreaker does not have enough context to point back to the last line wrap opportunity (after run #3).

[zalan]

Created attachment 386463 [details]
Patch

[WebKit Commit Bot]

Comment on attachment 386463 [details]
Patch

Clearing flags on attachment: 386463

Committed r253924: <https://trac.webkit.org/changeset/253924>

[WebKit Commit Bot]

All reviewed patches have been landed.  Closing bug.