Remove unwanted usings

src/Workspaces/CSharp/Portable/Formatting/Engine/Trivia/TriviaDataFactory.CodeShapeAnalyzer.cs

 // Copyright (c) Microsoft.  All Rights Reserved.  Licensed under the Apache License, Version 2.0.  See License.txt in the project root for license information.
 
-using System;
 using System.Diagnostics;
-using Microsoft.CodeAnalysis;
-using Microsoft.CodeAnalysis.CSharp;
 using Microsoft.CodeAnalysis.CSharp.Extensions;
-using Microsoft.CodeAnalysis.CSharp.Symbols;
 using Microsoft.CodeAnalysis.CSharp.Syntax;
 using Microsoft.CodeAnalysis.Formatting;
 using Microsoft.CodeAnalysis.Options;
 using Microsoft.CodeAnalysis.Shared.Extensions;
-using Microsoft.CodeAnalysis.Text;
 using Roslyn.Utilities;
 
 namespace Microsoft.CodeAnalysis.CSharp.Formatting