[Fetch API] Put body members directly on Response/Request

Source/modules/serviceworkers/Response.idl

Index: Source/modules/serviceworkers/Response.idl
diff --git a/Source/modules/serviceworkers/Response.idl b/Source/modules/serviceworkers/Response.idl
index 00fd8c05cda8bdb3b3667a74674ebd0593a7cced..f0aefb8c2ac231785920b838682624c2deadc0c6 100644
--- a/Source/modules/serviceworkers/Response.idl
+++ b/Source/modules/serviceworkers/Response.idl
@@ -11,6 +11,7 @@ enum ResponseType { "basic", "cors", "default", "error", "opaque" };
     // and URLSearchParams response bodies.
     Constructor(ScalarValueString body, optional Dictionary responseInitDict),
     Constructor(Blob? body, optional Dictionary responseInitDict),
+    ConstructorCallWith=ExecutionContext,
     RuntimeEnabled=ServiceWorker,
     Exposed=ServiceWorker,
     RaisesException=Constructor,
@@ -22,5 +23,6 @@ enum ResponseType { "basic", "cors", "default", "error", "opaque" };
     readonly attribute unsigned short status;
     readonly attribute ByteString statusText;
     readonly attribute Headers headers;
-    [CallWith=ExecutionContext] readonly attribute FetchBodyStream body;    
 };
+
+Response implements Body;