Open Radar

 
Summary:
Currently if you have a long IBInspectable such as:

```
@IBInspectable var dismissOnOutsideTap: Bool = true
```

And you try view the inspectables in interface builder, the label truncates at seemingly a fixed width. Even if you expand the utilities pane, the label does not get large enough to read the text. The only way to read it is by hovering over the label until the tooltip appears. It would be great if this label expanded, rather than the pop up button that often doesn't need to expand as much.

Steps to Reproduce:
1. Create a long IBInspectable such as `dismissOnOutsideTap`
2. View a class in IB that has this inspectable
3. Make the utilities pane wider and attempt to read the name of it

Expected Results:
The label expands either with the utility pane, or even when the utility pane is as small as possible

Actual Results:
The label never expands, making it hard to scan a list of inspectables

Version:
Xcode 9 9A235

Notes:
See the attached screenshots for examples