Copy byte arrays from storage to storage.

test/libsolidity/semanticTests/array/copying/bytes_inside_mappings.sol

@@ -3,6 +3,8 @@ contract c {
     function copy(uint from, uint to) public returns (bool) { data[to] = data[from]; return true; }
     mapping(uint => bytes) data;
 }
+// ====
+// compileViaYul: also
 // ----
 // set(uint256): 1, 2 -> true
 // set(uint256): 2, 2, 3, 4, 5 -> true