[part 2] Make classes and structures in modules fast-allocated.

Source/modules/webmidi/MIDIAccessor.h

Index: Source/modules/webmidi/MIDIAccessor.h
diff --git a/Source/modules/webmidi/MIDIAccessor.h b/Source/modules/webmidi/MIDIAccessor.h
index cb6e582cb3e9083b404ecf2afff1963131b9d118..f498c5860164e4564f0c9a6763ab274b16152872 100644
--- a/Source/modules/webmidi/MIDIAccessor.h
+++ b/Source/modules/webmidi/MIDIAccessor.h
@@ -33,6 +33,7 @@
 
 #include "public/platform/WebMIDIAccessor.h"
 #include "public/platform/WebMIDIAccessorClient.h"
+#include "wtf/FastAllocBase.h"
 #include "wtf/OwnPtr.h"
 #include "wtf/PassOwnPtr.h"
 
@@ -41,6 +42,7 @@ namespace blink {
 class MIDIAccessorClient;
 
 class MIDIAccessor final : public WebMIDIAccessorClient {
+    WTF_MAKE_FAST_ALLOCATED(MIDIAccessor);
 public:
     static PassOwnPtr<MIDIAccessor> create(MIDIAccessorClient*);