// The given entry must not be one from the header table, since it
// may get evicted. Tries to add the given entry to the header
// table, evicting entries if necessary as described in 3.3.3. index
// The given entry must not be one from the header table, since it
// may get evicted. Tries to add the given entry to the header
// table, evicting entries if necessary as described in 3.3.3. index