code review 7079043: all: use io.ByteWriter now that it exists

src/pkg/compress/lzw/writer.go

 // Copyright 2011 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
 package lzw
 
 import (
         "bufio"
         "errors"
         "fmt"
         "io"
 )
 
 // A writer is a buffered, flushable writer.
 type writer interface {
-        WriteByte(byte) error
+        io.ByteWriter
         Flush() error
 }
 
 // An errWriteCloser is an io.WriteCloser that always returns a given error.
 type errWriteCloser struct {
         err error
 }
 
 func (e *errWriteCloser) Write([]byte) (int, error) {
         return 0, e.err
@@ skipping 226 matching lines @@
                 w:         bw,
                 order:     order,
                 write:     write,
                 width:     1 + lw,
                 litWidth:  lw,
                 hi:        1<<lw + 1,
                 overflow:  1 << (lw + 1),
                 savedCode: invalidCode,
         }
 }