fix union test deps

mojo/public/interfaces/bindings/tests/BUILD.gn

Index: mojo/public/interfaces/bindings/tests/BUILD.gn
diff --git a/mojo/public/interfaces/bindings/tests/BUILD.gn b/mojo/public/interfaces/bindings/tests/BUILD.gn
index 06d0f9548014c11d8e2da029e06a3ed3f17735ec..0e086c39252467a84be83900964b9acdd93a684f 100644
--- a/mojo/public/interfaces/bindings/tests/BUILD.gn
+++ b/mojo/public/interfaces/bindings/tests/BUILD.gn
@@ -23,6 +23,7 @@ mojom("test_interfaces") {
     "test_native_types.mojom",
     "test_structs.mojom",
     "test_sync_methods.mojom",
+    "test_unions.mojom",
     "validation_test_interfaces.mojom",
   ]
   public_deps = [
@@ -148,13 +149,6 @@ mojom("test_struct_traits_interfaces") {
   ]
 }
 
-mojom("test_interfaces_experimental") {
-  testonly = true
-  sources = [
-    "test_unions.mojom",
-  ]
-}
-
 mojom("test_associated_interfaces") {
   # These files are not included in the test_interfaces target because
   # associated interfaces are not supported by all bindings languages yet.