Enable verifier on nested_flatbuffers

tests/fuzzer/flatbuffers_monster_fuzzer.cc

@@ -82,7 +82,6 @@ std::string do_test(const flatbuffers::IDLOptions &opts,
     TEST_EQ(true, MyGame::Example::VerifyMonsterBuffer(verifier));
     // FIXME: these are currently not being properly verified, so turn them off
     // for fuzzing until they are.
-    parser.opts.json_nested_flatbuffers = false;
     parser.opts.json_nested_flexbuffers = false;
     TEST_ASSERT(
         GenerateText(parser, parser.builder_.GetBufferPointer(), &jsongen));