internal/encoding/text: remove dead code

The newline field is unused. Remove it.

Change-Id: I8a6c6ea64eff718920102b87aa1fc66d8e736ac7
Reviewed-on: https://go-review.googlesource.com/c/protobuf/+/248297
Reviewed-by: Herbie Ong <herbie@google.com>
diff --git a/internal/encoding/text/encode.go b/internal/encoding/text/encode.go
index c4ba1c5..19dbcb0 100644
--- a/internal/encoding/text/encode.go
+++ b/internal/encoding/text/encode.go
@@ -32,7 +32,6 @@
 	encoderState
 
 	indent      string
-	newline     string // set to "\n" if len(indent) > 0
 	delims      [2]byte
 	outputASCII bool
 }
@@ -61,7 +60,6 @@
 			return nil, errors.New("indent may only be composed of space and tab characters")
 		}
 		e.indent = indent
-		e.newline = "\n"
 	}
 	switch delims {
 	case [2]byte{0, 0}: