Don't double-copy array when huffman decoding.

BAOS.toArray makes a defensive copy of its internal byte array buffer. If we don't do that, we can avoid a guaranteed extra array copy when huffman decoding. I profiled this change using hpack examples, and it increased the operations per second significantly enough to warrant the awkwardness of using byte arrays (IMHO).

Before
```
Benchmark                             Mode   Samples         Mean   Mean error    Units
decodeHuffmanExamples                 thrpt        50      938.633       11.216   ops/ms
```

After
```
Benchmark                             Mode   Samples         Mean   Mean error    Units
decodeHuffmanExamples                 thrpt        50     1102.408       22.488   ops/ms
```