compress/flate: remove unused woffset field.

Change-Id: Id0a12c76b0a6925f2926d38a1931157f9ef5f650
Reviewed-on: https://go-review.googlesource.com/20280Reviewed-by: Joe Tsai <joetsai@digital-static.net>
Run-TryBot: Joe Tsai <joetsai@digital-static.net>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

src/compress/flate/inflate.go

@@ -268,7 +268,6 @@ type decompressor struct {
 	// Input source.
 	r       Reader
 	roffset int64
-	woffset int64
 
 	// Input bits, in top of b.
 	b  uint32
@@ -352,7 +351,6 @@ func (f *decompressor) Read(b []byte) (int, error) {
 			return 0, f.err
 		}
 		f.step(f)
-		f.woffset += int64(len(f.toRead))
 	}
 }