Issue title: Code complete named param should be a String, but is offered a Typography
 Issue body: ![screen shot 2016-10-27 at 4 23 04 pm](https://cloud.githubusercontent.com/assets/5479/19771047/d6d6478e-9c61-11e6-978f-f36936218c45.png)

`fontFamily` is what I'm trying to complete. It can take a String. Notice how the first option is a Typography. If I hit enter, Typography is inserted.
 Comments: 
 Comment 0: This issue was moved to dart-lang/sdk#27688
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