[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 d0243d2055af42a7ae54773f9ee82c6beeb10a81..9f56935ee28d9930317561c4b54be9b70c2a8e4a 100644
--- a/Source/modules/serviceworkers/Response.idl
+++ b/Source/modules/serviceworkers/Response.idl
@@ -12,6 +12,7 @@ enum ResponseType { "basic", "cors", "default", "error", "opaque" };
     Constructor(Blob? body, optional Dictionary responseInitDict),
     Constructor(ArrayBuffer input, optional Dictionary requestInitDict),
     Constructor(ArrayBufferView input, optional Dictionary requestInitDict),
+    ConstructorCallWith=ExecutionContext,
     RuntimeEnabled=ServiceWorker,
     Exposed=ServiceWorker,
     RaisesException=Constructor,
@@ -23,5 +24,6 @@ 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;