Add interceptor support for symbols

src/elements.cc

Index: src/elements.cc
diff --git a/src/elements.cc b/src/elements.cc
index 76b9b03bf62d51a0ff4a59127f809f8f441fef84..c28a34173d81cbd7304fe5041f418d4aa960263a 100644
--- a/src/elements.cc
+++ b/src/elements.cc
@@ -751,7 +751,8 @@ class ElementsAccessorBase : public ElementsAccessor {
       Handle<Object> receiver,
       Handle<JSObject> holder,
       Handle<FixedArray> to,
-      Handle<FixedArrayBase> from) V8_FINAL V8_OVERRIDE {
+      Handle<FixedArrayBase> from,
+      FixedArray::KeyFilter filter) V8_FINAL V8_OVERRIDE {
     int len0 = to->length();
 #ifdef ENABLE_SLOW_DCHECKS
     if (FLAG_enable_slow_asserts) {
@@ -781,6 +782,11 @@ class ElementsAccessorBase : public ElementsAccessor {
             FixedArray);
 
         DCHECK(!value->IsTheHole());
+
+        if (filter == FixedArray::NON_SYMBOL_KEYS && value->IsSymbol()) {
+          continue;
+        }
+
         if (!HasKey(to, value)) {
           extra++;
         }
@@ -814,6 +820,9 @@ class ElementsAccessorBase : public ElementsAccessor {
             isolate, value,
             ElementsAccessorSubclass::GetImpl(receiver, holder, key, from),
             FixedArray);
+        if (filter == FixedArray::NON_SYMBOL_KEYS && value->IsSymbol()) {
+          continue;
+        }
         if (!value->IsTheHole() && !HasKey(to, value)) {
           result->set(len0 + index, *value);
           index++;