Oilpan: remove now-addressed PostMessageTimer fixme.

Source/core/frame/LocalDOMWindow.cpp

Index: Source/core/frame/LocalDOMWindow.cpp
diff --git a/Source/core/frame/LocalDOMWindow.cpp b/Source/core/frame/LocalDOMWindow.cpp
index a3fa464835ba8ae18bc1c89b38e7e65a66efebda..9ac315bbdcdfe24e60bb43b40ee15d7e2bfb1133 100644
--- a/Source/core/frame/LocalDOMWindow.cpp
+++ b/Source/core/frame/LocalDOMWindow.cpp
@@ -189,9 +189,6 @@ private:
         InspectorInstrumentation::traceAsyncCallbackCompleted(cookie);
     }
 
-    // FIXME: Oilpan: This raw pointer is safe because the PostMessageTimer is
-    // owned by the LocalDOMWindow. Ideally PostMessageTimer should be moved to
-    // the heap and use Member<LocalDOMWindow>.
     RawPtrWillBeMember<LocalDOMWindow> m_window;
     RefPtr<SerializedScriptValue> m_message;
     String m_origin;