BUG: Defaulting Style Manager values to em or %

When setting up the style manager to use only em and % for size related settings, whilst the units selector is changed, the value shown appears to me value x 16, so I set a value of 1 and it will result in a value of 16.

code:

const lineHeight = styleManager.getProperty('typography', 'line-height');
        lineHeight.set('units', [
            "",
            "em"
        ]);
        lineHeight.set('step', "0.1");
        lineHeight.set('min', 0.1);
        lineHeight.set('max', 100);

        lineHeight.set('unit', "");
        lineHeight.set('value', 1);

Here I would expect the line height to be set to 1 with a blank units value. but I get

![image](https://user-images.githubusercontent.com/60980627/91368477-4f676480-e85d-11ea-8f80-9df69afa9d55.png)




**What is the current behavior?**

Whist the presets work, the resulting value as shown in the style manager is showing the 'px' value






**Are you able to attach screenshots, screencasts or a live demo?**

[ X] Yes (attach)
[ ] No



This has been driving me nuts for ages.

thanks and this is a great tool.