Put Crossgen2 in sync with dotnet#54235

Author: trylek

src/coreclr/tools/Common/TypeSystem/Common/MetadataFieldLayoutAlgorithm.cs

@@ -782,13 +782,8 @@ public LayoutInt CalculateFieldBaseOffset(MetadataType type, bool requiresAlign8
             if (!type.IsValueType && type.HasBaseType)
             {
                 cumulativeInstanceFieldPos = type.BaseType.InstanceByteCountUnaligned;
-                if (!type.BaseType.InstanceByteCountUnaligned.IsIndeterminate)
+                if (!cumulativeInstanceFieldPos.IsIndeterminate)
                 {
-                    cumulativeInstanceFieldPos = type.BaseType.InstanceByteCountUnaligned;
-                    if (type.BaseType.IsZeroSizedReferenceType && ((MetadataType)type.BaseType).HasLayout())
-                    {
-                        cumulativeInstanceFieldPos += LayoutInt.One;
-                    }
                     AlignBaseOffsetIfNecessary(type, ref cumulativeInstanceFieldPos, requiresAlign8, requiresAlignedBase);
                 }
             }

src/coreclr/tools/Common/TypeSystem/Interop/IL/MarshalUtils.cs

@@ -23,8 +23,8 @@ public static bool IsBlittableType(TypeDesc type)
                 && !baseType.IsWellKnownType(WellKnownType.Object)
                 && !baseType.IsWellKnownType(WellKnownType.ValueType);
 
-            // Type is blittable only if parent is also blittable and is not empty.
-            if (hasNonTrivialParent && (!IsBlittableType(baseType) || baseType.IsZeroSizedReferenceType))
+            // Type is blittable only if parent is also blittable.
+            if (hasNonTrivialParent && !IsBlittableType(baseType))
             {
                 return false;
             }