Method iterator

Fleece/Mutable/HeapDict.cc:266–276

    HeapDict::iterator::iterator(const HeapDict *dict) noexcept
    :_sourceIter(dict->_source)
    ,_newIter(dict->_map.begin())
    ,_newEnd(dict->_map.end())
    ,_count(dict->count() + 1)
    ,_sharedKeys(dict->sharedKeys())
    {
        getSource();
        getNew();
        ++(*this);
    }

    HeapDict::iterator::iterator(const MutableDict *dict) noexcept
    :iterator((HeapDict*)HeapCollection::asHeapValue(dict))