-css-blocks-classnames is not a helper

Nobody has claimed this yet.

ember-cli: 3.3.0
node: 8.11.4
os: darwin x64

I have an ember-cli Glimmer app up and running and using the .20.0beta.0 and I'm running into a roadblock when trying to use states. I get this message. It looks like the template engine is looking for a helper that isn't there. Here's the console output.
```
app.js:1857 Uncaught (in promise) Error: Compile Error: -css-blocks-classnames is not a helper
at EXPRESSIONS.add (app.js:1857)
at Compilers.compile (app.js:1613)
at LazyOpcodeBuilder.expr (app.js:2538)
at EXPRESSIONS.add (app.js:1832)
at Compilers.compile (app.js:1613)
at LazyOpcodeBuilder.expr (app.js:2538)
at dynamicAttr (app.js:1800)
at STATEMENTS.add (app.js:1656)
at Compilers.compile (app.js:1613)
at CompilableTemplate.compile (app.js:2272)
```

CSS-Blocks has a lot of moving parts with the Ember-Cli part wrapping the Glimmer part wrapping the Core logic and I'm having trouble figuring out where this is breaking down.

I have a repo [here](https://github.com/WorkshopDigital/css-block-dummy) that demonstrates the problem.

Start with the linked css-block-dummy reproduction and trace the Ember CLI, Glimmer, and CSS-Blocks integration around the reported “-css-blocks-classnames is not a helper” error. Determine where the generated template expects the helper and where it should be made available; done means the reproduced state usage compiles without that error.

Written by the indexing model from the issue text.