Remove support for Object.observe

src/heap/heap.cc

Index: src/heap/heap.cc
diff --git a/src/heap/heap.cc b/src/heap/heap.cc
index b60bbdd1ec4c0c800ee297c5538d992953c483cd..51d09edf32b2f77286a23fa85edcd703f15af12c 100644
--- a/src/heap/heap.cc
+++ b/src/heap/heap.cc
@@ -2761,10 +2761,6 @@ void Heap::CreateInitialObjects() {
   // The symbol registry is initialized lazily.
   set_symbol_registry(Smi::FromInt(0));
 
-  // Allocate object to hold object observation state.
-  set_observation_state(*factory->NewJSObjectFromMap(
-      factory->NewMap(JS_OBJECT_TYPE, JSObject::kHeaderSize)));
-
   // Microtask queue uses the empty fixed array as a sentinel for "empty".
   // Number of queued microtasks stored in Isolate::pending_microtask_count().
   set_microtask_queue(empty_fixed_array());