C# Code coloring glitches after method that returns Task of tuple

_From @ahmadalli on December 23, 2017 13:25_

- VSCode Version: Code 1.19.1 (0759f77bb8d86658bc935a10a64f6182c5a1eeba, 2017-12-19T09:35:14.671Z)
- OS Version: Darwin x64 17.3.0
- Extensions:

Extension|Author (truncated)|Version
---|---|---
swagger-viewer|Arj|1.5.0
csharp|ms-|1.13.1

---

Steps to Reproduce:

1. Have a c# code with a method that returns task of a tuple.
2. this happens (take a look at the coloring of lines 73 to 98):


Reproduces without extensions: Yes (the image above is taken with `--disable-extensions` flag)

_Copied from original issue: Microsoft/vscode#40754_