Help needed to use custom browser to run uc browser

### Expected behaviour
Being able to use custom browser implementation to run uc browser.

### Actual behaviour
Not running UC browser

### Environment Details
- Karma version: 1.7.0
- Relevant part of your `karma.config.js` file:
```
module.exports = function (config) {
config.set({
browsers: ['C:/Program Files (x86)/UCBrowser/Application/UCBrowser.exe'],
});
};
```

### Steps to reproduce the behaviour
1. Run ng test
2. Get error that `Cannot load browser "Script": it is not registered! Perhaps you are missing some plugin?`

I get that I am not loading a script and an executable file instead. But I don't know how to run a custom browser with a script then. Can you guide me here?

Start with the shown karma.config.js browser setting and reproduce the `Cannot load browser "Script"` error when running `ng test`. Trace how Karma resolves browser names and executable paths, then consider the issue done when the custom UC Browser setup runs without the registration error.

Written by the indexing model from the issue text.