encoding/base64,xml: map/slice literals janitoring

Simplify slice/map literal expressions.
Caught with gofmt -d -s, fixed with gofmt -w -s

Change-Id: I639cfb02b1f57dea4087863df3995889c9371529
Reviewed-on: https://go-review.googlesource.com/13837Reviewed-by: Andrew Gerrand <adg@golang.org>

src/encoding/base64/base64_test.go

@@ -80,11 +80,11 @@ type encodingTest struct {
 }
 
 var encodingTests = []encodingTest{
-	encodingTest{StdEncoding, stdRef},
-	encodingTest{URLEncoding, urlRef},
-	encodingTest{RawStdEncoding, rawRef},
-	encodingTest{RawURLEncoding, rawUrlRef},
-	encodingTest{funnyEncoding, funnyRef},
+	{StdEncoding, stdRef},
+	{URLEncoding, urlRef},
+	{RawStdEncoding, rawRef},
+	{RawURLEncoding, rawUrlRef},
+	{funnyEncoding, funnyRef},
 }
 
 var bigtest = testpair{

src/encoding/xml/marshal_test.go

@@ -1695,7 +1695,7 @@ func TestRace9796(t *testing.T) {
 	for i := 0; i < 2; i++ {
 		wg.Add(1)
 		go func() {
-			Marshal(B{[]A{A{}}})
+			Marshal(B{[]A{{}}})
 			wg.Done()
 		}()
 	}