Reapply: "Make instanceof and Object.getPrototypeOf work for proxies,

src/objects-inl.h

 // Copyright 2011 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 2943 matching lines @@
       FromAddress(Memory::Address_at(location_of_address) - Code::kHeaderSize);
 }
 
 
 Object* Map::prototype() {
   return READ_FIELD(this, kPrototypeOffset);
 }
 
 
 void Map::set_prototype(Object* value, WriteBarrierMode mode) {
-  ASSERT(value->IsNull() || value->IsJSObject());
+  ASSERT(value->IsNull() || value->IsJSReceiver());
   WRITE_FIELD(this, kPrototypeOffset, value);
   CONDITIONAL_WRITE_BARRIER(GetHeap(), this, kPrototypeOffset, mode);
 }
 
 
 MaybeObject* Map::GetFastElementsMap() {
   if (has_fast_elements()) return this;
   Object* obj;
   { MaybeObject* maybe_obj = CopyDropTransitions();
     if (!maybe_obj->ToObject(&obj)) return maybe_obj;
@@ skipping 1323 matching lines @@
 #undef WRITE_INT_FIELD
 #undef READ_SHORT_FIELD
 #undef WRITE_SHORT_FIELD
 #undef READ_BYTE_FIELD
 #undef WRITE_BYTE_FIELD
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_OBJECTS_INL_H_