Fix a spec failure
Fix a spec failure

http://ci.rvm.jp/logfiles/brlog.trunk-test.20210216-182358
```
1)
$LOAD_PATH.resolve_feature_path raises LoadError if feature cannot be found FAILED
Expected LoadError but no exception was raised (nil was returned)
/tmp/ruby/v3/src/trunk-test/spec/ruby/language/predefined_spec.rb:1275:in `block (3 levels) in <top (required)>'
/tmp/ruby/v3/src/trunk-test/spec/ruby/language/predefined_spec.rb:1259:in `block in <top (required)>'
/tmp/ruby/v3/src/trunk-test/spec/ruby/language/predefined_spec.rb:1258:in `<top (required)>'
```

nobu/rubyspec,nobu/rubyspec,ruby/spec,ruby/spec,ruby/spec,nobu/rubyspec