Make JSProxies always be in slow mode

src/objects.h

 // Copyright 2015 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef V8_OBJECTS_H_
 #define V8_OBJECTS_H_
 
 #include <iosfwd>
 
 #include "src/allocation.h"
@@ skipping 3201 matching lines @@
   // Attempt to shrink hash table after removal of key.
   MUST_USE_RESULT static Handle<Derived> Shrink(Handle<Derived> table, Key key);
 
   // Ensure enough space for n additional elements.
   MUST_USE_RESULT static Handle<Derived> EnsureCapacity(
       Handle<Derived> table,
       int n,
       Key key,
       PretenureFlag pretenure = NOT_TENURED);
 
+  // Returns true if this table has sufficient capacity for adding n elements.
+  bool HasSufficientCapacity(int n);
+
   // Sets the capacity of the hash table.
   void SetCapacity(int capacity) {
     // To scale a computed hash code to fit within the hash table, we
     // use bit-wise AND with a mask, so the capacity must be positive
     // and non-zero.
     DCHECK(capacity > 0);
     DCHECK(capacity <= kMaxCapacity);
     set(kCapacityIndex, Smi::FromInt(capacity));
   }
 
@@ skipping 179 matching lines @@
   int NextEnumerationIndex() {
     return Smi::cast(this->get(kNextEnumerationIndexIndex))->value();
   }
 
   // Creates a new dictionary.
   MUST_USE_RESULT static Handle<Derived> New(
       Isolate* isolate,
       int at_least_space_for,
       PretenureFlag pretenure = NOT_TENURED);
 
+  // Ensures that a new dictionary is created when the capacity is checked.
+  void SetRequiresCopyOnCapacityChange();
+
   // Ensure enough space for n additional elements.
   static Handle<Derived> EnsureCapacity(Handle<Derived> obj, int n, Key key);
 
 #ifdef OBJECT_PRINT
   void Print(std::ostream& os);  // NOLINT
 #endif
   // Returns the key (slow).
   Object* SlowReverseLookup(Object* value);
 
   // Sets the entry to (key, value) pair.
@@ skipping 7311 matching lines @@
     }
     return value;
   }
 };
 
 
 }  // NOLINT, false-positive due to second-order macros.
 }  // NOLINT, false-positive due to second-order macros.
 
 #endif  // V8_OBJECTS_H_