C#: Cleanup private imports in LibraryTypeDataFlow.

Author: michaelnebel

csharp/ql/lib/semmle/code/csharp/dataflow/LibraryTypeDataFlow.qll

@@ -7,12 +7,9 @@ private import semmle.code.csharp.frameworks.System
 private import semmle.code.csharp.frameworks.system.Collections
 private import semmle.code.csharp.frameworks.system.collections.Generic
 private import semmle.code.csharp.frameworks.system.linq.Expressions
-private import semmle.code.csharp.frameworks.system.Net
 private import semmle.code.csharp.frameworks.system.Text
 private import semmle.code.csharp.frameworks.system.runtime.CompilerServices
 private import semmle.code.csharp.frameworks.system.threading.Tasks
-private import semmle.code.csharp.frameworks.system.Web
-private import semmle.code.csharp.frameworks.system.web.ui.WebControls
 private import semmle.code.csharp.dataflow.internal.DataFlowPrivate
 private import semmle.code.csharp.dataflow.internal.DataFlowPublic
 private import semmle.code.csharp.dataflow.internal.DelegateDataFlow