Remove support for Object.observe

src/runtime/runtime-internal.cc

 // Copyright 2014 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/runtime/runtime-utils.h"
 
 #include "src/arguments.h"
 #include "src/ast/prettyprinter.h"
 #include "src/bootstrapper.h"
 #include "src/conversions.h"
@@ skipping 485 matching lines @@
   HandleScope scope(isolate);
   DCHECK_EQ(0, args.length());
   std::stringstream stats_stream;
   isolate->counters()->runtime_call_stats()->Print(stats_stream);
   Handle<String> result =
       isolate->factory()->NewStringFromAsciiChecked(stats_stream.str().c_str());
   isolate->counters()->runtime_call_stats()->Reset();
   return *result;
 }
 
+RUNTIME_FUNCTION(Runtime_EnqueueMicrotask) {
+  HandleScope scope(isolate);
+  DCHECK(args.length() == 1);
+  CONVERT_ARG_HANDLE_CHECKED(JSFunction, microtask, 0);
+  isolate->EnqueueMicrotask(microtask);
+  return isolate->heap()->undefined_value();
+}
+
+RUNTIME_FUNCTION(Runtime_RunMicrotasks) {
+  HandleScope scope(isolate);
+  DCHECK(args.length() == 0);
+  isolate->RunMicrotasks();
+  return isolate->heap()->undefined_value();
+}
 }  // namespace internal
 }  // namespace v8