Follow-up to 270645@main to address review feedback from Darin. Use Vector constructor / WTF::map() when possible instead of an append*() function. There are a couple of cases in 270645@main where I keep using append*() even though they were calling reserveInitialCapacity() before because the vectors in question have an inline buffer and doing a Vector move assignment may end up having to copy the values in the inline buffers over.