Remove support for Object.observe

src/objects-printer.cc

 // Copyright 2012 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.
 
 #include "src/objects.h"
 
 #include "src/disasm.h"
 #include "src/disassembler.h"
 #include "src/interpreter/bytecodes.h"
 #include "src/objects-inl.h"
@@ skipping 478 matching lines @@
   if (is_stable()) os << "\n - stable_map";
   if (is_dictionary_map()) os << "\n - dictionary_map";
   if (has_hidden_prototype()) os << "\n - has_hidden_prototype";
   if (has_named_interceptor()) os << " - named_interceptor";
   if (has_indexed_interceptor()) os << "\n - indexed_interceptor";
   if (is_undetectable()) os << "\n - undetectable";
   if (is_callable()) os << "\n - callable";
   if (is_constructor()) os << "\n - constructor";
   if (is_access_check_needed()) os << "\n - access_check_needed";
   if (!is_extensible()) os << "\n - non-extensible";
-  if (is_observed()) os << "\n - observed";
   if (is_prototype_map()) {
     os << "\n - prototype_map";
     os << "\n - prototype info: " << Brief(prototype_info());
   } else {
     os << "\n - back pointer: " << Brief(GetBackPointer());
   }
   os << "\n - instance descriptors " << (owns_descriptors() ? "(own) " : "")
      << "#" << NumberOfOwnDescriptors() << ": "
      << Brief(instance_descriptors());
   if (FLAG_unbox_double_fields) {
@@ skipping 799 matching lines @@
       os << "(transition to non-extensible)";
     } else if (key == heap->sealed_symbol()) {
       os << "(transition to sealed)";
     } else if (key == heap->frozen_symbol()) {
       os << "(transition to frozen)";
     } else if (key == heap->elements_transition_symbol()) {
       os << "(transition to " << ElementsKindToString(target->elements_kind())
          << ")";
     } else if (key == heap->strict_function_transition_symbol()) {
       os << " (transition to strict function)";
-    } else if (key == heap->observed_symbol()) {
-      os << " (transition to Object.observe)";
     } else {
       PropertyDetails details = GetTargetDetails(key, target);
       os << "(transition to ";
       if (details.location() == kDescriptor) {
         os << "immutable ";
       }
       os << (details.kind() == kData ? "data" : "accessor");
       if (details.location() == kDescriptor) {
         Object* value =
             target->instance_descriptors()->GetValue(target->LastAdded());
         os << " " << Brief(value);
       }
       os << "), attrs: " << details.attributes();
     }
     os << " -> " << Brief(target);
   }
 }
 
 
 void JSObject::PrintTransitions(std::ostream& os) {  // NOLINT
   Object* transitions = map()->raw_transitions();
   int num_transitions = TransitionArray::NumberOfTransitions(transitions);
   if (num_transitions == 0) return;
   os << "\n - transitions";
   TransitionArray::PrintTransitions(os, transitions, false);
 }
 #endif  // defined(DEBUG) || defined(OBJECT_PRINT)
 }  // namespace internal
 }  // namespace v8