Fix for-in for large indexes and indexes on proxies

src/objects-inl.h

Index: src/objects-inl.h
diff --git a/src/objects-inl.h b/src/objects-inl.h
index a2b0189d3d0ca559912a8846f1adad63d3a7b9ea..50d02f9f655e887b10cf5dc4e290d0a343cd7480 100644
--- a/src/objects-inl.h
+++ b/src/objects-inl.h
@@ -275,6 +275,24 @@ bool Object::HasValidElements() {
 }
 
 
+bool Object::KeyEquals(Object* second) {
+  Object* first = this;
+  if (second->IsNumber()) {
+    if (first->IsNumber()) return first->Number() == second->Number();
+    Object* temp = first;
+    first = second;
+    second = temp;
+  }
+  if (first->IsNumber()) {
+    DCHECK_LE(0, first->Number());
+    uint32_t expected = static_cast<uint32_t>(first->Number());
+    uint32_t index;
+    return Name::cast(second)->AsArrayIndex(&index) && index == expected;
+  }
+  return Name::cast(first)->Equals(Name::cast(second));
+}
+
+
 Handle<Object> Object::NewStorageFor(Isolate* isolate,
                                      Handle<Object> object,
                                      Representation representation) {