goprotobuf: Use local imports for testdata package.

TBR=r
CC=golang-dev
http://codereview.appspot.com/5832043
diff --git a/proto/text_parser_test.go b/proto/text_parser_test.go
index 3848790..c178449 100644
--- a/proto/text_parser_test.go
+++ b/proto/text_parser_test.go
@@ -35,8 +35,8 @@
 	"reflect"
 	"testing"
 
+	. "./testdata"
 	. "code.google.com/p/goprotobuf/proto"
-	. "code.google.com/p/goprotobuf/proto/testdata"
 )
 
 type UnmarshalTextTest struct {