clean up proj refs

Author: mythz

src/ServiceStack.Text/ServiceStack.Text.Core.csproj

@@ -17,15 +17,14 @@
   </PropertyGroup>
   <ItemGroup>
     <PackageReference Include="System.Memory" Version="4.5.3" />
+    <PackageReference Include="Microsoft.CSharp" Version="4.5.0" />
   </ItemGroup>
   <ItemGroup Condition=" '$(TargetFramework)' == 'netstandard2.0' ">
     <PackageReference Include="System.Runtime" Version="4.3.1" />
-    <PackageReference Include="Microsoft.CSharp" Version="4.5.0" />
   </ItemGroup>
   <ItemGroup Condition=" '$(TargetFramework)' == 'netcoreapp2.1' ">
     <PackageReference Include="System.Runtime" Version="4.3.1" />
     <PackageReference Include="System.Reflection.Emit" Version="4.3.0" />
     <PackageReference Include="System.Reflection.Emit.LightWeight" Version="4.3.0" />
-    <PackageReference Include="Microsoft.CSharp" Version="4.5.0" />
   </ItemGroup>
 </Project>

src/ServiceStack.Text/ServiceStack.Text.csproj

@@ -16,19 +16,17 @@
   </PropertyGroup>
   <ItemGroup>
     <PackageReference Include="System.Memory" Version="4.5.3" />
+    <PackageReference Include="Microsoft.CSharp" Version="4.5.0" />
   </ItemGroup>
   <ItemGroup Condition=" '$(TargetFramework)' == 'net45' ">
     <Reference Include="System.Configuration" />
-    <Reference Include="Microsoft.CSharp" />
   </ItemGroup>
   <ItemGroup Condition=" '$(TargetFramework)' == 'netstandard2.0' ">
     <PackageReference Include="System.Runtime" Version="4.3.1" />
-    <PackageReference Include="Microsoft.CSharp" Version="4.5.0" />
   </ItemGroup>
   <ItemGroup Condition=" '$(TargetFramework)' == 'netcoreapp2.1' ">
     <PackageReference Include="System.Runtime" Version="4.3.1" />
     <PackageReference Include="System.Reflection.Emit" Version="4.3.0" />
     <PackageReference Include="System.Reflection.Emit.LightWeight" Version="4.3.0" />
-    <PackageReference Include="Microsoft.CSharp" Version="4.5.0" />
   </ItemGroup>
 </Project>

src/ServiceStack.Text/StringExtensions.cs

@@ -226,14 +226,12 @@ public static string ToRot13(this string value)
 
         public static string WithTrailingSlash(this string path)
         {
-            if (String.IsNullOrEmpty(path))
+            if (path == null)
                 throw new ArgumentNullException(nameof(path));
+            if (path == "")
+                return "/";
 
-            if (path[path.Length - 1] != '/')
-            {
-                return path + "/";
-            }
-            return path;
+            return path[path.Length - 1] != '/' ? path + "/" : path;
         }
 
         public static string AppendPath(this string uri, params string[] uriComponents)