Add conversion to WasmAstNode for wasm Objects.

src/wasm/timestamp.rs

@@ -28,3 +28,9 @@ to_wasm!(
         })
     }
 );
+
+impl<'s, 'p> Into<WasmAstNode<'s, 'p>> for WasmTimestamp<'s, 'p> {
+    fn into(self) -> WasmAstNode<'s, 'p> {
+        WasmAstNode::Timestamp(self)
+    }
+}