Convert between Dart and JavaScript SerializedScriptValues on postMessage.

lib/html/src/dart2js_Conversions.dart

Index: lib/html/src/dart2js_Conversions.dart
diff --git a/lib/html/src/dart2js_Conversions.dart b/lib/html/src/dart2js_Conversions.dart
index 7abe1c0e5cf741034e55e289fee64de9eaf36466..b9eed1607f2268bda1135ad171a3a5a8acf7fa9f 100644
--- a/lib/html/src/dart2js_Conversions.dart
+++ b/lib/html/src/dart2js_Conversions.dart
@@ -129,16 +129,21 @@ _convertDartToNative_IDBKey(dartKey) {
 
 
 
-// May modify original.  If so, action is idempotent.
+/// May modify original.  If so, action is idempotent.
 _convertNativeToDart_IDBAny(object) {
   return _convertNativeToDart_AcceptStructuredClone(object);
 }
 
-/// Converts a Dart value into
+/// Converts a Dart value into a JavaScript SerializedScriptValue.
 _convertDartToNative_SerializedScriptValue(value) {
   return _convertDartToNative_PrepareForStructuredClone(value);
 }
 
+/// May modify original.  If so, action is idempotent.
+_convertNativeToDart_SerializedScriptValue(object) {
+  return _convertNativeToDart_AcceptStructuredClone(object);
+}
+
 
 /**
  * Converts a Dart value into a JavaScript SerializedScriptValue.  Returns the