Ensure JSProxy correctness for PrototypeIterator uses

src/ic/ic.cc

Index: src/ic/ic.cc
diff --git a/src/ic/ic.cc b/src/ic/ic.cc
index f4ab98839d32510116e06d64c6bee1dc8ee19fed..7a859346b457c5f01766c2fe764d6a30389734c0 100644
--- a/src/ic/ic.cc
+++ b/src/ic/ic.cc
@@ -2255,7 +2255,8 @@ MaybeHandle<Object> KeyedStoreIC::Store(Handle<Object> object,
           // from peeking in the code bits of the handlers.
           if (!FLAG_vector_stores) ValidateStoreMode(stub);
         } else {
-          TRACE_GENERIC_IC(isolate(), "KeyedStoreIC", "dictionary prototype");
+          TRACE_GENERIC_IC(isolate(), "KeyedStoreIC",
+                           "dictionary or proxy prototype");
         }
       } else {
         TRACE_GENERIC_IC(isolate(), "KeyedStoreIC", "non-smi-like key");