internal/encoding/json: remove duplicate test

This test was accidentally duplicated in CL 569356.

Change-Id: I0e2f81fbebe9b4c37bf6d28615e0bf51d28cfc4c
Reviewed-on: https://go-review.googlesource.com/c/protobuf/+/607777
Auto-Submit: Michael Stapelberg <stapelberg@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Christian Höppner <hoeppi@google.com>
diff --git a/internal/encoding/json/decode_test.go b/internal/encoding/json/decode_test.go
index 64ffd37..28d3fba 100644
--- a/internal/encoding/json/decode_test.go
+++ b/internal/encoding/json/decode_test.go
@@ -1194,13 +1194,6 @@
 			},
 		},
 		{
-			in: `{""`,
-			want: []R{
-				{V: ObjectOpen},
-				{E: errEOF},
-			},
-		},
-		{
 			in: `{"":`,
 			want: []R{
 				{V: ObjectOpen},