Motivation:
DefaultHeaders entries maintains two linked lists. 1 for overall insertion order
and 1 for "in bucket" order. DefaultHeaders#valueIterator removal (introduced in 1d9090aab231ab737bd6459e0369b30d752296b2) only reliably
removes the entry from the overall insertion order, but may not remove from the
bucket unless the element is the first entry.
Modifications:
- DefaultHeaders$ValueIterator should track 2 elements behind the next entry so
that the single linked "in bucket" list can be patched up when removing the
previous entry.
Result:
More correct DefaultHeaders#valueIterator removal.
3c11af965a