Syntax highlighting lost after certain comments

[DustinCampbell]

From @cateyes99 on July 23, 2017 3:27

Environment data

dotnet --info output:

.NET Command Line Tools (1.0.1)

Product Information:
 Version:            1.0.1
 Commit SHA-1 hash:  005db40cd1

Runtime Environment:
 OS Name:     Mac OS X
 OS Version:  10.11
 OS Platform: Darwin
 RID:         osx.10.11-x64
 Base Path:   /usr/local/share/dotnet/sdk/1.0.1

VS Code version: 1.14.2
C# Extension version: 1.11.0

Steps to reproduce

Create below C# snippet

Expected behavior

The method F2() should still have correct syntax highlighting.

Actual behavior

The method F2() doesn't have correct syntax highlighting.

I notice:
if I remove the Line 9, the the syntax highlighting is back:

or remove the namespance, the the syntax highlighting is also back:

Copied from original issue: dotnet/vscode-csharp#1659