def syntax doesn't work with keywords in objects

### Description

```imba
let sorters = {

# works
new: do $1.time

# doesn't work
def new
$1.time

}
```

### Reproduction

_No response_

### System Environment

_No response_

No files, tests, or entry points are named. Start by locating the Imba parser or compiler entry point and reproduce the object example, comparing the working `new: do $1.time` form with `def new`. Done means the `def` form works for the `new` object key consistently with the equivalent `do` form.

Written by the indexing model from the issue text.