Remove usings.

src/Features/CSharp/Portable/Completion/CompletionProviders/SymbolCompletionProvider.cs

@@ -3,21 +3,17 @@
 using System;
 using System.Collections.Generic;
 using System.Collections.Immutable;
-using System.IO;
-using System.Linq;
 using System.Threading;
 using System.Threading.Tasks;
 using Microsoft.CodeAnalysis.Completion;
 using Microsoft.CodeAnalysis.Completion.Providers;
 using Microsoft.CodeAnalysis.CSharp.Extensions;
 using Microsoft.CodeAnalysis.CSharp.Extensions.ContextQuery;
-using Microsoft.CodeAnalysis.CSharp.Syntax;
 using Microsoft.CodeAnalysis.Options;
 using Microsoft.CodeAnalysis.Recommendations;
 using Microsoft.CodeAnalysis.Shared.Extensions;
 using Microsoft.CodeAnalysis.Shared.Extensions.ContextQuery;
 using Microsoft.CodeAnalysis.Text;
-using Roslyn.Utilities;
 
 namespace Microsoft.CodeAnalysis.CSharp.Completion.Providers
 {