Clean JS function results cache on each major GC.

src/heap.h

Index: src/heap.h
diff --git a/src/heap.h b/src/heap.h
index cdfa6cca9bd808c5e6d429fe22c03ee0f4c281ce..902fc77ee6961c2517604a780a83a7a25a146401 100644
--- a/src/heap.h
+++ b/src/heap.h
@@ -1178,6 +1178,8 @@ class Heap : public AllStatic {
                                           HeapObject* target,
                                           int size);
 
+  static void ClearJSFunctionResultCaches();
+
 #if defined(DEBUG) || defined(ENABLE_LOGGING_AND_PROFILING)
   // Record the copy of an object in the NewSpace's statistics.
   static void RecordCopiedObject(HeapObject* obj);