Oilpan: Remove OffHeapCollectionTrait

Source/core/css/CSSPropertySourceData.h

Index: Source/core/css/CSSPropertySourceData.h
diff --git a/Source/core/css/CSSPropertySourceData.h b/Source/core/css/CSSPropertySourceData.h
index 5e06c5a0514646bf9a70e9eaab87938ea23113b6..49323b60a7ad03b5c8242e52a0d033e22e2de3e8 100644
--- a/Source/core/css/CSSPropertySourceData.h
+++ b/Source/core/css/CSSPropertySourceData.h
@@ -75,7 +75,12 @@ struct CSSStyleSourceData : public RefCountedWillBeGarbageCollected<CSSStyleSour
         return adoptRefWillBeNoop(new CSSStyleSourceData());
     }
 
-    DEFINE_INLINE_TRACE() { visitor->trace(propertyData); }
+    DEFINE_INLINE_TRACE()
+    {
+#if ENABLE(OILPAN)
+        visitor->trace(propertyData);
+#endif
+    }
 
     WillBeHeapVector<CSSPropertySourceData> propertyData;
 };
@@ -97,7 +102,12 @@ struct CSSMediaQuerySourceData : public RefCountedWillBeGarbageCollected<CSSMedi
         return adoptRefWillBeNoop(new CSSMediaQuerySourceData());
     }
 
-    DEFINE_INLINE_TRACE() { visitor->trace(expData); }
+    DEFINE_INLINE_TRACE()
+    {
+#if ENABLE(OILPAN)
+        visitor->trace(expData);
+#endif
+    }
 
     WillBeHeapVector<CSSMediaQueryExpSourceData> expData;
 };
@@ -108,7 +118,12 @@ struct CSSMediaSourceData : public RefCountedWillBeGarbageCollected<CSSMediaSour
         return adoptRefWillBeNoop(new CSSMediaSourceData());
     }
 
-    DEFINE_INLINE_TRACE() { visitor->trace(queryData); }
+    DEFINE_INLINE_TRACE()
+    {
+#if ENABLE(OILPAN)
+        visitor->trace(queryData);
+#endif
+    }
 
     WillBeHeapVector<RefPtrWillBeMember<CSSMediaQuerySourceData>> queryData;
 };