Revert "_assetref setunsafe (unstable buggy)"

This reverts commit 89d359e0078bbec8c84cad07950ad5df6df46fc3.

Source/Engine/Content/AssetReference.h

@@ -217,17 +217,6 @@ public:
     {
         OnSet(asset);
     }
-
-    /// <summary>
-    /// Sets the asset reference without binding the events.
-    /// This should only be used cautiously in cases where the reference needs to be held for a short time (for example in while marshalling managed types).
-    /// </summary>
-    /// <param name="asset">The asset.</param>
-    void SetUnsafe(T* asset)
-    {
-        ASSERT(_asset == nullptr || asset == nullptr);
-        _asset = asset;
-    }
 };
 
 template<typename T>