Comment 40 for bug 677551

Are you talking about ClearTextRun?

  if (!(textRun->GetFlags() & gfxTextRunWordCache::TEXT_IN_CACHE)) {
    // Remove it now because it's not doing anything useful
    gTextRuns->RemoveFromCache(textRun);
    delete textRun;

So we only remove it from gTextRuns (an nsExpirationTracker) if the textrun is NOT referenced from the gfxTextRunWordCache.

(In reply to comment #29)
> If I hit enter a few lines from the end I get two textruns constructed per line
> between me and the end. roc, is that expected?

No, that sounds like a definite problem. What should happen is that in CharacterDataChanged we clear the textruns from the caret to the end, then when we reflow the line with the caret (or maybe the line before the caret), we reconstruct text runs for those lines, and then no more textrun construction happens.