html/charset: replace EUC-KR test

The old test for EUC-KR was copied from the first web page that I could
find that was encoded in EUC-KR; the new one is the first line of
golang.org/x/text/internal/testtext.Korean.

Change-Id: I3de076256c935088a06138056cde216190766a6d
Reviewed-on: https://go-review.googlesource.com/18063Reviewed-by: Marcel van Lohuizen <mpvl@golang.org>

html/charset/charset_test.go

@@ -67,7 +67,7 @@ var testCases = []testCase{
 	{"ｲｳｴｵｶ", "\xb2\xb3\xb4\xb5\xb6", "SJIS"},
 	{"これは漢字です。", "\xa4\xb3\xa4\xec\xa4\u03f4\xc1\xbb\xfa\xa4\u01e4\xb9\xa1\xa3", "EUC-JP"},
 	{"Hello, 世界!", "Hello, \x1b$B@$3&\x1b(B!", "ISO-2022-JP"},
-	{"네이트 | 즐거움의 시작, 슈파스(Spaβ) NATE", "\xb3\xd7\xc0\xcc\xc6\xae | \xc1\xf1\xb0\xc5\xbf\xf2\xc0\xc7 \xbd\xc3\xc0\xdb, \xbd\xb4\xc6\xc4\xbd\xba(Spa\xa5\xe2) NATE", "EUC-KR"},
+	{"다음과 같은 조건을 따라야 합니다: 저작자표시", "\xb4\xd9\xc0\xbd\xb0\xfa \xb0\xb0\xc0\xba \xc1\xb6\xb0\xc7\xc0\xbb \xb5\xfb\xb6\xf3\xbe\xdf \xc7մϴ\xd9: \xc0\xfa\xc0\xdb\xc0\xdaǥ\xbd\xc3", "EUC-KR"},
 }
 
 func TestDecode(t *testing.T) {