...which had apparently been unused ever since the function's introduction in
86ef4422 "INTEGRATION: CWS onlineupdate3," even
though the function's code had always been careful to clip the value to
m_aAddButtons.size() (which was now detected by clang-tidy's
clang-analyzer-deadcode.DeadStores)

Change-Id: Ic3542aaef04d059125d997cdc5e199d5edb1184a