[2c] Replace Body::readAsyncFromBlob with readAsyncFromFetchDataConsumerHandle

Source/modules/fetch/FetchDataLoader.h

Index: Source/modules/fetch/FetchDataLoader.h
diff --git a/Source/modules/fetch/FetchDataLoader.h b/Source/modules/fetch/FetchDataLoader.h
index bee7bf49d6e38f82c6d97f840ea15416d010c3ec..3f7d054a69ca2f1624d787290fbb010edd3fde54 100644
--- a/Source/modules/fetch/FetchDataLoader.h
+++ b/Source/modules/fetch/FetchDataLoader.h
@@ -28,7 +28,7 @@ namespace blink {
 // - FetchDataLoader takes the ownership of |handle|'s reader but not |handle|.
 class MODULES_EXPORT FetchDataLoader : public GarbageCollectedFinalized<FetchDataLoader> {
 public:
-    class Client : public GarbageCollectedMixin {
+    class MODULES_EXPORT Client : public GarbageCollectedMixin {
     public:
         virtual ~Client() { }