compress/flate: use correct table for size estimation

The incorrect table was used for estimating output size.
This can give suboptimal selection of entropy encoder in rare cases.

Change-Id: I8b358200f2d1f9a3f9b79a44269d7be704e1d2d9
Reviewed-on: https://go-review.googlesource.com/31172Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

src/compress/flate/huffman_bit_writer.go

@@ -520,7 +520,7 @@ func (w *huffmanBitWriter) writeBlockDynamic(tokens []token, eof bool, input []b
 	// the literalEncoding and the offsetEncoding.
 	w.generateCodegen(numLiterals, numOffsets, w.literalEncoding, w.offsetEncoding)
 	w.codegenEncoding.generate(w.codegenFreq[:], 7)
-	size, numCodegens := w.dynamicSize(w.literalEncoding, huffOffset, 0)
+	size, numCodegens := w.dynamicSize(w.literalEncoding, w.offsetEncoding, 0)
 
 	// Store bytes, if we don't get a reasonable improvement.
 	if ssize, storable := w.storedSize(input); storable && ssize < (size+size>>4) {