Make JSProxies always be in slow mode

src/objects.cc

Index: src/objects.cc
diff --git a/src/objects.cc b/src/objects.cc
index dff101c54e0c2ec8573e43e818f7b60a263c1b66..673a70854b123098854507df080ba62bcdfeca7d 100644
--- a/src/objects.cc
+++ b/src/objects.cc
@@ -17159,14 +17159,8 @@ Handle<Derived> HashTable<Derived, Shape, Key>::EnsureCapacity(
   Isolate* isolate = table->GetIsolate();
   int capacity = table->Capacity();
   int nof = table->NumberOfElements() + n;
-  int nod = table->NumberOfDeletedElements();
-  // Return if:
-  //   50% is still free after adding n elements and
-  //   at most 50% of the free elements are deleted elements.
-  if (nod <= (capacity - nof) >> 1) {
-    int needed_free = nof >> 1;
-    if (nof + needed_free <= capacity) return table;
-  }
+
+  if (table->HasSufficientCapacity(n)) return table;
 
   const int kMinCapacityForPretenure = 256;
   bool should_pretenure = pretenure == TENURED ||
@@ -17183,6 +17177,22 @@ Handle<Derived> HashTable<Derived, Shape, Key>::EnsureCapacity(
 }
 
 
+template <typename Derived, typename Shape, typename Key>
+bool HashTable<Derived, Shape, Key>::HasSufficientCapacity(int n) {
+  int capacity = Capacity();
+  int nof = NumberOfElements() + n;
+  int nod = NumberOfDeletedElements();
+  // Return true if:
+  //   50% is still free after adding n elements and
+  //   at most 50% of the free elements are deleted elements.
+  if (nod <= (capacity - nof) >> 1) {
+    int needed_free = nof >> 1;
+    if (nof + needed_free <= capacity) return true;
+  }
+  return false;
+}
+
+
 template<typename Derived, typename Shape, typename Key>
 Handle<Derived> HashTable<Derived, Shape, Key>::Shrink(Handle<Derived> table,
                                                        Key key) {
@@ -17349,6 +17359,9 @@ template Handle<UnseededNumberDictionary>
 Dictionary<UnseededNumberDictionary, UnseededNumberDictionaryShape, uint32_t>::
     EnsureCapacity(Handle<UnseededNumberDictionary>, int, uint32_t);
 
+template void Dictionary<NameDictionary, NameDictionaryShape,
+                         Handle<Name> >::SetRequiresCopyOnCapacityChange();
+
 template Handle<NameDictionary>
 Dictionary<NameDictionary, NameDictionaryShape, Handle<Name> >::
     EnsureCapacity(Handle<NameDictionary>, int, Handle<Name>);
@@ -18077,7 +18090,17 @@ Dictionary<Derived, Shape, Key>::GenerateNewEnumerationIndices(
 }
 
 
-template<typename Derived, typename Shape, typename Key>
+template <typename Derived, typename Shape, typename Key>
+void Dictionary<Derived, Shape, Key>::SetRequiresCopyOnCapacityChange() {
+  DCHECK_EQ(0, DerivedHashTable::NumberOfElements());
+  DCHECK_EQ(0, DerivedHashTable::NumberOfDeletedElements());
+  // Make sure that HashTable::EnsureCapacity will create a copy.
+  DerivedHashTable::SetNumberOfDeletedElements(DerivedHashTable::Capacity());
+  DCHECK(!DerivedHashTable::HasSufficientCapacity(1));
+}
+
+
+template <typename Derived, typename Shape, typename Key>
 Handle<Derived> Dictionary<Derived, Shape, Key>::EnsureCapacity(
     Handle<Derived> dictionary, int n, Key key) {
   // Check whether there are enough enumeration indices to add n elements.