Remove support for Object.observe

src/objects-printer.cc

Index: src/objects-printer.cc
diff --git a/src/objects-printer.cc b/src/objects-printer.cc
index 45d023cedf77412fa713dccccd8ca7bcb2683dde..551beb2e6239ba0d1cab4c61dce12272335f89e9 100644
--- a/src/objects-printer.cc
+++ b/src/objects-printer.cc
@@ -496,7 +496,6 @@ void Map::MapPrint(std::ostream& os) {  // NOLINT
   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());
@@ -1316,8 +1315,6 @@ void TransitionArray::PrintTransitions(std::ostream& os, Object* transitions,
          << ")";
     } 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 ";