Incorrect font-style returned for text layers by javascript api
While trying to get font-family and font-weight for an text layer, 
e.g.  If I create a new text layer with font ass roboto with type thin. 
Copy CSS attributes from sketch UI returns this : 

font-family: Roboto-Thin;
font-size: 24px;
color: #101010;
letter-spacing: 0;

but JavaScript api on exporting text layer returns these font style properties: 

opacity: 1
fontSize: 24
fontFamily: Roboto
paragraphSpacing: 0
kerning: 0
fontWeight: 3
alignment: left
fontStretch: condensed

Ideally roboto-thin should return font-weight as 100 
See : https://fonts.google.com/specimen/Roboto
Also sketch api should give font-family as either roboto-thin or 
fontFamily=Roboto with fontWeight:100 or fontWeight=1 
Clearly Sketch JavaScript API is returning incorrect fontFamily and/or font-weight values.

**Additional Information:**

- Sketch version: Version 65.1 (95501)
- macOS version: 10.14.6 (18G4032)