Revert revision 27542 "Make Dart_IdentityEqual live up to its spec and not leak boxing implementati…

runtime/vm/dart_api_impl.cc

Index: runtime/vm/dart_api_impl.cc
===================================================================
--- runtime/vm/dart_api_impl.cc	(revision 27544)
+++ runtime/vm/dart_api_impl.cc	(working copy)
@@ -497,18 +497,8 @@
 DART_EXPORT bool Dart_IdentityEquals(Dart_Handle obj1, Dart_Handle obj2) {
   Isolate* isolate = Isolate::Current();
   CHECK_ISOLATE(isolate);
-  {
-    NoGCScope ngc;
-    if (Api::UnwrapHandle(obj1) == Api::UnwrapHandle(obj2)) {
-      return true;
-    }
-  }
-  const Object& object1 = Object::Handle(isolate, Api::UnwrapHandle(obj1));
-  const Object& object2 = Object::Handle(isolate, Api::UnwrapHandle(obj2));
-  if (object1.IsInstance() && object2.IsInstance()) {
-    return Instance::Cast(object1).IsIdenticalTo(Instance::Cast(object2));
-  }
-  return false;
+  NoGCScope ngc;
+  return Api::UnwrapHandle(obj1) == Api::UnwrapHandle(obj2);
 }