encoding/xml: do not escape newlines

There is no need to escape newlines in char data -
it makes the XML larger and harder to read.

Change-Id: I1c1fcee1bdffc705c7428f89ca90af8085d6fb73
Reviewed-on: https://go-review.googlesource.com/9310Reviewed-by: Nigel Tao <nigeltao@golang.org>
Reviewed-by: Russ Cox <rsc@golang.org>

src/encoding/xml/marshal.go

@@ -209,7 +209,7 @@ func (enc *Encoder) EncodeToken(t Token) error {
 			return err
 		}
 	case CharData:
-		EscapeText(p, t)
+		escapeText(p, t, false)
 	case Comment:
 		if bytes.Contains(t, endComment) {
 			return fmt.Errorf("xml: EncodeToken of Comment containing --> marker")

src/encoding/xml/marshal_test.go

@@ -1297,7 +1297,7 @@ var encodeTokenTests = []struct {
 	toks: []Token{
 		CharData(" \t\n"),
 	},
-	want: ` 	
`,
+	want: " 	\n",
 }, {
 	desc: "comment",
 	toks: []Token{

src/encoding/xml/xml.go

@@ -1863,6 +1863,13 @@ var (
 // EscapeText writes to w the properly escaped XML equivalent
 // of the plain text data s.
 func EscapeText(w io.Writer, s []byte) error {
+	return escapeText(w, s, true)
+}
+
+// escapeText writes to w the properly escaped XML equivalent
+// of the plain text data s. If escapeNewline is true, newline
+// characters will be escaped.
+func escapeText(w io.Writer, s []byte, escapeNewline bool) error {
 	var esc []byte
 	last := 0
 	for i := 0; i < len(s); {
@@ -1882,6 +1889,9 @@ func EscapeText(w io.Writer, s []byte) error {
 		case '\t':
 			esc = esc_tab
 		case '\n':
+			if !escapeNewline {
+				continue
+			}
 			esc = esc_nl
 		case '\r':
 			esc = esc_cr