Revert "Added Expressions dependency"

This reverts commit 3e5193c3b7.

src/Discord.Net/Net/Converters/DiscordContractResolver.cs

@@ -6,7 +6,6 @@ using System.Collections.Generic;
 using System.IO;
 using System.Linq;
 using System.Reflection;
-using System.Linq.Expressions;
 
 namespace Discord.Net.Converters
 {
@@ -29,11 +28,11 @@ namespace Discord.Net.Converters
                     var typeInput = propInfo.DeclaringType;
                     var innerTypeOutput = type.GenericTypeArguments[0];
 
-                    var parentArg = Expression.Parameter(typeof(object));
-                    var optional = Expression.Property(Expression.Convert(parentArg, property.DeclaringType), member as PropertyInfo);
-                    var isSpecified = Expression.Property(optional, "IsSpecified");
-                    var lambda = Expression.Lambda<Func<object, bool>>(isSpecified, parentArg).Compile();
-                    property.ShouldSerialize = x => lambda(x);
+                    var getter = typeof(Func<,>).MakeGenericType(typeInput, type);
+                    var getterDelegate = propInfo.GetMethod.CreateDelegate(getter);
+                    var shouldSerialize = _shouldSerialize.MakeGenericMethod(typeInput, innerTypeOutput);
+                    var shouldSerializeDelegate = (Func<object, Delegate, bool>)shouldSerialize.CreateDelegate(typeof(Func<object, Delegate, bool>));
+                    property.ShouldSerialize = x => shouldSerializeDelegate(x, getterDelegate);
 
                     var converterType = typeof(OptionalConverter<>).MakeGenericType(innerTypeOutput).GetTypeInfo();
                     var instanceField = converterType.GetDeclaredField("Instance");
@@ -97,5 +96,10 @@ namespace Discord.Net.Converters
 
             return null;
         }
+
+        private static bool ShouldSerialize<TOwner, TValue>(object owner, Delegate getter)
+        {
+            return (getter as Func<TOwner, Optional<TValue>>)((TOwner)owner).IsSpecified;
+        }
     }
 }

src/Discord.Net/project.json

@@ -25,7 +25,6 @@
     "System.Collections.Immutable": "1.2.0-rc2-24027",
     "System.IO.Compression": "4.1.0-rc2-24027",
     "System.IO.FileSystem": "4.0.1-rc2-24027",
-    "System.Linq.Expressions": "4.0.11-rc2-24027",
     "System.Net.Http": "4.0.1-rc2-24027",
     "System.Net.WebSockets.Client": "4.0.0-rc2-24027",
     "System.Reflection.Extensions": "4.0.1-rc2-24027",