Revert "Refactor Damage to use Protoypes (#4262)"

This reverts commit 20bf5739a9.

Content.Shared/Damage/DamageClass.cs

@@ -0,0 +1,38 @@
+using System;
+using System.Collections.Generic;
+using System.Collections.Immutable;
+using System.Linq;
+using Robust.Shared.Serialization;
+
+namespace Content.Shared.Damage
+{
+    [Serializable, NetSerializable]
+    public enum DamageClass
+    {
+        Brute,
+        Burn,
+        Toxin,
+        Airloss,
+        Genetic
+    }
+
+    public static class DamageClassExtensions
+    {
+        public static ImmutableList<DamageType> ToTypes(this DamageClass @class)
+        {
+            return DamageSystem.ClassToType[@class];
+        }
+
+        public static Dictionary<DamageClass, T> ToNewDictionary<T>() where T : struct
+        {
+            return Enum.GetValues(typeof(DamageClass))
+                .Cast<DamageClass>()
+                .ToDictionary(@class => @class, _ => default(T));
+        }
+
+        public static Dictionary<DamageClass, int> ToNewDictionary()
+        {
+            return ToNewDictionary<int>();
+        }
+    }
+}