Remove support for Object.observe

src/runtime/runtime-collections.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/conversions-inl.h"
 #include "src/factory.h"
 
@@ skipping 350 matching lines @@
     DisallowHeapAllocation no_gc;
     int count = 0;
     for (int i = 0; count < max_values && i < table->Capacity(); i++) {
       Handle<Object> key(table->KeyAt(i), isolate);
       if (table->IsKey(*key)) values->set(count++, *key);
     }
     DCHECK_EQ(max_values, count);
   }
   return *isolate->factory()->NewJSArrayWithElements(values);
 }
-
-
-RUNTIME_FUNCTION(Runtime_ObservationWeakMapCreate) {
-  HandleScope scope(isolate);
-  DCHECK(args.length() == 0);
-  Handle<JSWeakMap> weakmap = isolate->factory()->NewJSWeakMap();
-  JSWeakCollection::Initialize(weakmap, isolate);
-  return *weakmap;
-}
 }  // namespace internal
 }  // namespace v8