Merge "Avoid unnecessary allocation in VectorImpl" into main

    size_t new_size;

    LOG_ALWAYS_FATAL_IF(__builtin_sub_overflow(mCount, amount, &new_size));

    if (new_size < (capacity() / 2)) {

    const size_t prev_capacity = capacity();

    if (new_size < (prev_capacity / 2) && prev_capacity > kMinVectorCapacity) {

        // NOTE: (new_size * 2) is safe because capacity didn't overflow and

        // new_size < (capacity / 2)).

        const size_t new_capacity = max(kMinVectorCapacity, new_size * 2);