Since we've [disabled](https://github.com/ampproject/amphtml/blob/33ca73f014a388cca2d94ec19cd868d62334de2a/build-system/runner/src/org/ampproject/AmpCommandLineRunner.java#L78) closure's `inlineProperties` transform, we lose the ability to DCE based on constant properties:

```js
class Ex {
  constructor() {
    /** @Private @const {boolean} */
    this.foo_ = false;
  }

  test() {
    if (this.foo_) {
      // We expect this to be DCE'd (since foo_ is always false)
      // But closure won't do it.
      alert('foo');
    }
  }
}
```

This inlines the private const properties _before_ closure sees them, so that they can be DCE'd:

```js
// Input
class Ex {
  constructor() {
    /** @Private @const {boolean} */
    this.foo_ = false;
  }

  test() {
    if (this.foo_) {
      alert('foo');
    }
  }
}

// Output
class Ex {
  constructor() {
  }

  test() {
    if (false) {
      alert('foo');
    }
  }
}
```