Get rid of this code. Doesn't seem necessary anymore.

sdk/lib/_internal/compiler/implementation/js_backend/emitter.dart

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 part of js_backend;
 
 /**
  * A function element that represents a closure call. The signature is copied
  * from the given element.
  */
@@ skipping 2865 matching lines @@
           js.if_(
               js('(typeof receiver) != "object"'),
               js.return_(js('receiver'))));
 
       // if (receiver instanceof $.Object) return receiver;
       // return $.getNativeInterceptor(receiver);
       block.statements.add(
           js.if_(js('receiver instanceof #',
                     js(namer.isolateAccess(compiler.objectClass))),
                  js.return_(js('receiver'))));
-
-      // TODO(sra): Fold this 'Object' check into the `getNativeInterceptor`
-      // check by patching `Object.prototype` with a special hook function.
-      // TODO(9556): This test is needed in plain non-browser code because
-      // 'holders' are not Dart classes.
-      block.statements.add(
-          js.if_(
-              js('Object.getPrototypeOf(receiver) === Object.prototype'),
-              buildReturnInterceptor(backend.jsInterceptorClass)));
-
       block.statements.add(
           js.return_(
               js(namer.isolateAccess(backend.getNativeInterceptorMethod))(
                   ['receiver'])));
 
     } else {
       ClassElement jsUnknown = backend.jsUnknownClass;
       if (compiler.codegenWorld.instantiatedClasses.contains(jsUnknown)) {
         block.statements.add(
             js.if_(js('!(receiver instanceof #)',
@@ skipping 733 matching lines @@
 
 const String HOOKS_API_USAGE = """
 // The code supports the following hooks:
 // dartPrint(message)   - if this function is defined it is called
 //                        instead of the Dart [print] method.
 // dartMainRunner(main) - if this function is defined, the Dart [main]
 //                        method will not be invoked directly.
 //                        Instead, a closure that will invoke [main] is
 //                        passed to [dartMainRunner].
 """;