core/state: remove IsConst from StorageItem

pkg/core/state/storage_item.go

@@ -6,18 +6,15 @@ import (
 
 // StorageItem is the value to be stored with read-only flag.
 type StorageItem struct {
-	Value   []byte
-	IsConst bool
+	Value []byte
 }
 
 // EncodeBinary implements Serializable interface.
 func (si *StorageItem) EncodeBinary(w *io.BinWriter) {
 	w.WriteVarBytes(si.Value)
-	w.WriteBool(si.IsConst)
 }
 
 // DecodeBinary implements Serializable interface.
 func (si *StorageItem) DecodeBinary(r *io.BinReader) {
 	si.Value = r.ReadVarBytes()
-	si.IsConst = r.ReadBool()
 }

pkg/core/state/storage_item_test.go

@@ -8,8 +8,7 @@ import (
 
 func TestEncodeDecodeStorageItem(t *testing.T) {
 	storageItem := &StorageItem{
-		Value:   []byte{},
-		IsConst: false,
+		Value: []byte{1, 2, 3},
 	}
 
 	testserdes.EncodeDecodeBinary(t, storageItem, new(StorageItem))