webp: fix tests for webp/nycbcra deprecation.

The previous commit (00fe24ef "webp/nycbcra: deprecate package") was
incomplete.

Change-Id: I6af5e1633b9c291e72b02877b308eae6e5624ef5
Reviewed-on: https://go-review.googlesource.com/21441
Reviewed-by: Nigel Tao <nigeltao@golang.org>

 cmd/webp-manual-test/main.go | 5 ++---
 webp/decode_test.go          | 6 ++----
 2 files changed, 4 insertions(+), 7 deletions(-)

diff --git a/cmd/webp-manual-test/main.go b/cmd/webp-manual-test/main.go
index 296c763..acb2815 100644
--- a/cmd/webp-manual-test/main.go
+++ b/cmd/webp-manual-test/main.go
@@ -26,7 +26,6 @@ import (
 	"strings"
 
 	"golang.org/x/image/webp"
-	"golang.org/x/image/webp/nycbcra"
 )
 
 var (
@@ -161,12 +160,12 @@ func encodePAM(gotImage image.Image) ([]byte, error) {
 func encodePGM(gotImage image.Image) ([]byte, error) {
 	var (
 		m  *image.YCbCr
-		ma *nycbcra.Image
+		ma *image.NYCbCrA
 	)
 	switch g := gotImage.(type) {
 	case *image.YCbCr:
 		m = g
-	case *nycbcra.Image:
+	case *image.NYCbCrA:
 		m = &g.YCbCr
 		ma = g
 	default:
diff --git a/webp/decode_test.go b/webp/decode_test.go
index 4b69f90..ad65b10 100644
--- a/webp/decode_test.go
+++ b/webp/decode_test.go
@@ -13,8 +13,6 @@ import (
 	"os"
 	"strings"
 	"testing"
-
-	"golang.org/x/image/webp/nycbcra"
 )
 
 // hex is like fmt.Sprintf("% x", x) but also inserts dots every 16 bytes, to
@@ -54,11 +52,11 @@ func testDecodeLossy(t *testing.T, tc string, withAlpha bool) {
 
 	var (
 		m0 *image.YCbCr
-		a0 *nycbcra.Image
+		a0 *image.NYCbCrA
 		ok bool
 	)
 	if withAlpha {
-		a0, ok = img0.(*nycbcra.Image)
+		a0, ok = img0.(*image.NYCbCrA)
 		if ok {
 			m0 = &a0.YCbCr
 		}