Dart how to match and then replace a regexp

This may be a silly question, but I can't find any reference on how to replace a text after being matched by a regexp using Dart's RegExp.

Basically what I'm trying to do is like this: I have a text like this

'{name : aName, hobby : [fishing, playing_guitar]}'

I want to match the string using this pattern \b\w+\b, then replace using "$&". I expect the output to be like:

'{"name" : "aName", "hobby" : ["fishing", "playing_guitar"]}'

So later I can use dart:json's parse to turn that to a Map.

Maybe I missed something. Does anyone know how I can achieve this replacement?