Remove unnecessary package references (#835)

Author: pakrym

src/Microsoft.AspNetCore.Http.Extensions/Microsoft.AspNetCore.Http.Extensions.csproj

@@ -1,4 +1,4 @@
-<Project Sdk="Microsoft.NET.Sdk">
+<Project Sdk="Microsoft.NET.Sdk">
 
   <Import Project="..\..\build\common.props" />
 
@@ -17,7 +17,6 @@
 
   <ItemGroup>
     <PackageReference Include="Microsoft.Extensions.FileProviders.Abstractions" Version="$(AspNetCoreVersion)" />
-    <PackageReference Include="System.Buffers" Version="$(CoreFxVersion)" />
   </ItemGroup>
 
 </Project>

src/Microsoft.AspNetCore.Http.Features/Microsoft.AspNetCore.Http.Features.csproj

@@ -1,4 +1,4 @@
-<Project Sdk="Microsoft.NET.Sdk">
+<Project Sdk="Microsoft.NET.Sdk">
 
   <Import Project="..\..\build\common.props" />
 
@@ -13,8 +13,6 @@
 
   <ItemGroup>
     <PackageReference Include="Microsoft.Extensions.Primitives" Version="$(AspNetCoreVersion)" />
-    <PackageReference Include="System.ComponentModel" Version="$(CoreFxVersion)" />
-    <PackageReference Include="System.Security.Principal" Version="$(CoreFxVersion)" />
   </ItemGroup>
 
 </Project>

src/Microsoft.AspNetCore.Http/Microsoft.AspNetCore.Http.csproj

@@ -1,4 +1,4 @@
-<Project Sdk="Microsoft.NET.Sdk">
+<Project Sdk="Microsoft.NET.Sdk">
 
   <Import Project="..\..\build\common.props" />
 
@@ -22,7 +22,6 @@
     <PackageReference Include="Microsoft.Extensions.ObjectPool" Version="$(AspNetCoreVersion)" />
     <PackageReference Include="Microsoft.Extensions.Options" Version="$(AspNetCoreVersion)" />
     <PackageReference Include="Microsoft.Extensions.TaskCache.Sources" Version="$(AspNetCoreVersion)" PrivateAssets="All" />
-    <PackageReference Include="System.Buffers" Version="$(CoreFxVersion)" />
   </ItemGroup>
 
 </Project>

src/Microsoft.Net.Http.Headers/Microsoft.Net.Http.Headers.csproj

@@ -1,4 +1,4 @@
-<Project Sdk="Microsoft.NET.Sdk">
+<Project Sdk="Microsoft.NET.Sdk">
 
   <Import Project="..\..\build\common.props" />
 
@@ -14,8 +14,6 @@
 
   <ItemGroup>
     <PackageReference Include="Microsoft.Extensions.Primitives" Version="$(AspNetCoreVersion)" />
-    <PackageReference Include="System.Buffers" Version="$(CoreFxVersion)" />
-    <PackageReference Include="System.Diagnostics.Contracts" Version="$(CoreFxVersion)" />
   </ItemGroup>
 
 </Project>