Ref T12287. See D17361. That fixed a mostly-theoretical bug with crumbs named things like "MMMMMMMMMMMMMMMMMMMM", but caused a less-theoretical buggy side effect in Safari.

For now, just keep the "MMMMMMMM" crumbs around since that's the easiest/least-bad/safest fix prior to the release cut. We can fix this more broadly when we have more time to look at it.

Looked at profiles, saw the entire name for "hector" and the too-long-crumb for "MMMMM".