Macro implementation when using triggers is not working

This works:

```scala
discoveredDist <<= (dist in ReactiveRuntime)
  .storeAs(discoveredDist in Global)
  .triggeredBy(dist in ReactiveRuntime)
```

however this doesn't:

```scala
discoveredDist := (dist in ReactiveRuntime)
  .storeAs(discoveredDist in Global)
  .triggeredBy(dist in ReactiveRuntime)
  .value
```
