Add code to test the wasm code path without actually dropping into wasm.

src/wasm/standard_properties.rs

@@ -6,7 +6,7 @@ use serde::Serialize;
 use super::to_wasm::ToWasmContext;
 use super::to_wasm::ToWasmStandardProperties;
 
-#[derive(Serialize, Deserialize)]
+#[derive(Debug, Serialize, Deserialize)]
 pub(crate) struct WasmStandardProperties {
     begin: usize,
     end: usize,