Enable Oilpan by default in modules/filesystem/

Source/modules/filesystem/FileWriter.h

Index: Source/modules/filesystem/FileWriter.h
diff --git a/Source/modules/filesystem/FileWriter.h b/Source/modules/filesystem/FileWriter.h
index 17ad7cf00abd24c2c22640e783692ba919689d3f..c3a8cea99979f61f542c64fa98f25aaeb1d0ffbe 100644
--- a/Source/modules/filesystem/FileWriter.h
+++ b/Source/modules/filesystem/FileWriter.h
@@ -48,10 +48,10 @@ class ExceptionState;
 class ExecutionContext;
 
 class FileWriter FINAL : public FileWriterBase, public ScriptWrappable, public ActiveDOMObject, public EventTargetWithInlineData, public blink::WebFileWriterClient {
-    REFCOUNTED_EVENT_TARGET(FileWriterBase);
+    DEFINE_EVENT_TARGET_REFCOUNTING(RefCountedGarbageCollected<FileWriterBase>);
     WILL_BE_USING_GARBAGE_COLLECTED_MIXIN(FileWriter);
 public:
-    static PassRefPtrWillBeRawPtr<FileWriter> create(ExecutionContext*);
+    static FileWriter* create(ExecutionContext*);
 
     enum ReadyState {
         INIT = 0,