Remove support for Object.observe

src/objects-inl.h

 // 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.
 //
 // Review notes:
 //
 // - The use of macros in these inline functions may seem superfluous
 // but it is absolutely needed to make sure gcc generates optimal
 // code. gcc is not happy when attempting to inline too deep.
 //
@@ skipping 4426 matching lines @@
 void Map::set_is_undetectable() {
   set_bit_field(bit_field() | (1 << kIsUndetectable));
 }
 
 
 bool Map::is_undetectable() {
   return ((1 << kIsUndetectable) & bit_field()) != 0;
 }
 
 
-void Map::set_is_observed() { set_bit_field(bit_field() | (1 << kIsObserved)); }
-
-bool Map::is_observed() { return ((1 << kIsObserved) & bit_field()) != 0; }
-
-
 void Map::set_has_named_interceptor() {
   set_bit_field(bit_field() | (1 << kHasNamedInterceptor));
 }
 
 
 bool Map::has_named_interceptor() {
   return ((1 << kHasNamedInterceptor) & bit_field()) != 0;
 }
 
 
@@ skipping 3356 matching lines @@
 #undef WRITE_INT64_FIELD
 #undef READ_BYTE_FIELD
 #undef WRITE_BYTE_FIELD
 #undef NOBARRIER_READ_BYTE_FIELD
 #undef NOBARRIER_WRITE_BYTE_FIELD
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_OBJECTS_INL_H_